after about 10m after staring my application the CPU increases to ~20%.
Here are the Garbage Collector stats. What I can see is that the CPU usage increases when at that point when the YGC increases way faster than before. It starts at Timestamp 706.3

In this chart you can see that Eden space is not used and Old generation is not modified anymore. If I force the application to do something, the CPU is going down to ~2-3% till Eden space is empty again.

So it seems the Garbage Collector is using more CPU when there is “nothing to do”? The “Problem” started at the point I lowered the Maximum Heap Size for the application.

Timestamp           S0C         S1C         S0U         S1U          EC           EU           OC           OU          MC         MU       CCSC      CCSU     YGC     YGCT     FGC    FGCT     CGC    CGCT       GCT
           16.0         0.0      3072.0         0.0      3072.0      22528.0      15360.0      65536.0      43952.0    54080.0    53642.5    7232.0    7024.0     20     0.274     0     0.000    18     0.075     0.349
           26.1         0.0      1024.0         0.0        95.3       6144.0       5120.0     115712.0      55567.5    70144.0    69676.4    9408.0    9162.8     38     0.451     0     0.000    30     0.155     0.607
           36.1         0.0      1024.0         0.0        68.4      56320.0       1024.0      65536.0      64739.0    70400.0    69915.3    9408.0    9166.6     60     0.579     0     0.000    38     0.198     0.777
           46.1         0.0      1024.0         0.0        68.4      33792.0       2048.0      88064.0      87267.0    70400.0    69935.6    9408.0    9167.7     60     0.579     0     0.000    38     0.198     0.777
           56.1         0.0      1024.0         0.0        68.4      13312.0       3072.0     108544.0     107747.0    70464.0    69941.6    9408.0    9167.7     60     0.579     0     0.000    38     0.198     0.777
           66.1         0.0      1024.0         0.0        27.5       6144.0          0.0     115712.0      64739.0    70464.0    69947.3    9408.0    9167.7     61     0.589     0     0.000    38     0.198     0.787
           76.1         0.0      1024.0         0.0        27.5       6144.0       1024.0     115712.0      85219.0    70464.0    69956.8    9408.0    9167.7     61     0.589     0     0.000    38     0.198     0.787
           86.1         0.0      1024.0         0.0        27.5       6144.0       3072.0     115712.0     105699.0    70464.0    69968.2    9408.0    9168.2     61     0.589     0     0.000    38     0.198     0.787
           96.1         0.0      1024.0         0.0        27.2      59392.0       1024.0      62464.0      61971.0    70464.0    69971.1    9408.0    9168.2     62     0.595     0     0.000    38     0.198     0.793
          106.1         0.0      1024.0         0.0        28.7      59392.0       1024.0      62464.0      57875.0    70464.0    69721.9    9408.0    9114.1     64     0.608     0     0.000    40     0.222     0.830
          116.1         0.0      1024.0         0.0        28.7      45056.0       1024.0      77824.0      77331.0    70464.0    69722.3    9408.0    9114.1     64     0.608     0     0.000    40     0.222     0.830
          126.1         0.0      1024.0         0.0        28.7      24576.0       2048.0      97280.0      96787.0    70464.0    69727.8    9408.0    9114.1     64     0.608     0     0.000    40     0.222     0.830
          136.1         0.0      1024.0         0.0        30.4       6144.0          0.0     115712.0      53779.0    70464.0    69731.0    9408.0    9114.1     65     0.619     0     0.000    40     0.222     0.841
          146.1         0.0      1024.0         0.0        30.4       6144.0       1024.0     115712.0      74259.0    70464.0    69740.8    9408.0    9114.6     65     0.619     0     0.000    40     0.222     0.841
          156.1         0.0      1024.0         0.0        30.4       6144.0       2048.0     115712.0      94739.0    70464.0    69741.8    9408.0    9114.6     65     0.619     0     0.000    40     0.222     0.841
          166.1         0.0      1024.0         0.0        39.6      60416.0          0.0      61440.0      50355.5    70464.0    69759.0    9408.0    9114.6     66     0.627     0     0.000    40     0.222     0.849
          176.1         0.0      1024.0         0.0        30.7      52224.0       1024.0      69632.0      68787.5    70464.0    69760.0    9408.0    9114.6     67     0.632     0     0.000    42     0.232     0.863
          186.1         0.0      1024.0         0.0        30.7      31744.0       2048.0      90112.0      89267.5    70464.0    69760.5    9408.0    9114.6     67     0.632     0     0.000    42     0.232     0.863
          196.2         0.0      1024.0         0.0        30.7      11264.0       3072.0     110592.0     109747.5    70464.0    69760.9    9408.0    9114.6     67     0.632     0     0.000    42     0.232     0.863
          206.2         0.0      1024.0         0.0        30.2       6144.0          0.0     115712.0      64691.5    70464.0    69761.2    9408.0    9114.6     68     0.642     0     0.000    42     0.232     0.874
          216.2         0.0      1024.0         0.0        30.2       6144.0       1024.0     115712.0      85171.5    70464.0    69771.8    9408.0    9114.6     68     0.642     0     0.000    42     0.232     0.874
          226.2         0.0      1024.0         0.0        30.2       6144.0       2048.0     115712.0     105651.5    70464.0    69779.6    9408.0    9114.6     68     0.642     0     0.000    42     0.232     0.874
          236.2         0.0      1024.0         0.0        32.2      62464.0       1024.0      59392.0      59143.5    70464.0    69781.5    9408.0    9114.6     70     0.666     0     0.000    44     0.241     0.907
          246.2         0.0      1024.0         0.0        32.2      41984.0       2048.0      79872.0      79623.5    70464.0    69785.4    9408.0    9114.6     70     0.666     0     0.000    44     0.241     0.907
          256.2         0.0      1024.0         0.0        32.2      21504.0       3072.0     100352.0     100103.5    70528.0    69795.1    9408.0    9114.6     70     0.666     0     0.000    44     0.241     0.907
          266.2         0.0      1024.0         0.0        42.1       6144.0          0.0     115712.0      52999.5    70528.0    69817.3    9408.0    9114.6     71     0.671     0     0.000    44     0.241     0.912
          276.2         0.0      1024.0         0.0        42.1       6144.0       1024.0     115712.0      73479.5    70528.0    69839.1    9408.0    9114.6     71     0.671     0     0.000    44     0.241     0.912
          286.2         0.0      1024.0         0.0        42.1       6144.0       2048.0     115712.0      93959.5    70528.0    69849.0    9408.0    9114.6     71     0.671     0     0.000    44     0.241     0.912
          296.2         0.0      1024.0         0.0        42.1       6144.0       3072.0     115712.0     114439.5    70528.0    69849.0    9408.0    9114.6     71     0.671     0     0.000    44     0.241     0.912
          306.2         0.0      1024.0         0.0        32.8      54272.0       1024.0      67584.0      67029.5    70528.0    69850.4    9408.0    9114.6     73     0.682     0     0.000    46     0.251     0.933
          316.2         0.0      1024.0         0.0        32.8      33792.0       3072.0      88064.0      87509.5    70528.0    69863.9    9408.0    9116.2     73     0.682     0     0.000    46     0.251     0.933
          326.2         0.0      1024.0         0.0        32.8      13312.0       3072.0     108544.0     107989.5    70528.0    69865.7    9408.0    9116.2     73     0.682     0     0.000    46     0.251     0.933
          336.2         0.0      1024.0         0.0        44.2       6144.0          0.0     115712.0      60897.0    70528.0    69866.9    9408.0    9116.2     74     0.688     0     0.000    46     0.251     0.939
          346.2         0.0      1024.0         0.0        44.2       6144.0       1024.0     115712.0      81377.0    70528.0    69866.9    9408.0    9116.2     74     0.688     0     0.000    46     0.251     0.939
          356.2         0.0      1024.0         0.0        44.2       6144.0       2048.0     115712.0     101857.0    70528.0    69873.8    9408.0    9116.8     74     0.688     0     0.000    46     0.251     0.939
          366.2         0.0      1024.0         0.0        44.3      62464.0       1024.0      59392.0      54518.0    70528.0    69873.8    9408.0    9116.8     76     0.701     0     0.000    48     0.263     0.965
          376.2         0.0      1024.0         0.0        44.3      46080.0       2048.0      75776.0      74998.0    70528.0    69874.7    9408.0    9116.8     76     0.701     0     0.000    48     0.263     0.965
          386.2         0.0      1024.0         0.0        44.3      25600.0       2048.0      96256.0      95478.0    70528.0    69874.7    9408.0    9116.8     76     0.701     0     0.000    48     0.263     0.965
          396.2         0.0      1024.0         0.0        42.3       6144.0          0.0     115712.0      48388.0    70528.0    69881.9    9408.0    9116.8     77     0.711     0     0.000    48     0.263     0.974
          406.2         0.0      1024.0         0.0        42.3       6144.0       1024.0     115712.0      68868.0    70528.0    69895.8    9408.0    9116.8     77     0.711     0     0.000    48     0.263     0.974
          416.2         0.0      1024.0         0.0        42.3       6144.0       1024.0     115712.0      89348.0    70528.0    69895.8    9408.0    9116.8     77     0.711     0     0.000    48     0.263     0.974
          426.2         0.0      1024.0         0.0        42.3       6144.0       2048.0     115712.0     109828.0    70528.0    69898.5    9408.0    9116.8     77     0.711     0     0.000    48     0.263     0.974
          436.2         0.0      1024.0         0.0        32.6      59392.0       1024.0      62464.0      62149.5    70528.0    69898.9    9408.0    9116.8     79     0.725     0     0.000    50     0.273     0.998
          446.2         0.0      1024.0         0.0        32.6      38912.0       2048.0      82944.0      82629.5    70528.0    69898.9    9408.0    9116.8     79     0.725     0     0.000    50     0.273     0.998
          456.2         0.0      1024.0         0.0        32.6      18432.0       3072.0     103424.0     103109.5    70528.0    69899.3    9408.0    9116.8     79     0.725     0     0.000    50     0.273     0.998
          466.2         0.0      1024.0         0.0        28.2       6144.0          0.0     115712.0      53968.5    70528.0    69905.0    9408.0    9116.8     80     0.731     0     0.000    50     0.273     1.004
          476.2         0.0      1024.0         0.0        28.2       6144.0       1024.0     115712.0      74448.5    70528.0    69905.4    9408.0    9116.8     80     0.731     0     0.000    50     0.273     1.004
          486.2         0.0      1024.0         0.0        28.2       6144.0       2048.0     115712.0      94928.5    70528.0    69905.4    9408.0    9116.8     80     0.731     0     0.000    50     0.273     1.004
          496.2         0.0      1024.0         0.0        28.7      63488.0          0.0      58368.0      47532.0    70592.0    69909.4    9408.0    9116.8     81     0.738     0     0.000    50     0.273     1.011
          506.2         0.0      1024.0         0.0        27.4      55296.0       1024.0      66560.0      65964.0    70592.0    69916.5    9408.0    9116.8     82     0.747     0     0.000    52     0.282     1.029
          516.2         0.0      1024.0         0.0        27.4      34816.0       2048.0      87040.0      86444.0    70592.0    69930.6    9408.0    9116.8     82     0.747     0     0.000    52     0.282     1.029
          526.2         0.0      1024.0         0.0        27.4      14336.0       3072.0     107520.0     106924.0    70592.0    69932.4    9408.0    9116.8     82     0.747     0     0.000    52     0.282     1.029
          536.2         0.0      1024.0         0.0        31.6       6144.0          0.0     115712.0      57779.0    70592.0    69934.8    9408.0    9116.8     83     0.757     0     0.000    52     0.282     1.039
          546.2         0.0      1024.0         0.0        31.6       6144.0       1024.0     115712.0      78259.0    70592.0    69936.0    9408.0    9116.8     83     0.757     0     0.000    52     0.282     1.039
          556.2         0.0      1024.0         0.0        31.6       6144.0       2048.0     115712.0      98739.0    70592.0    69937.2    9408.0    9116.8     83     0.757     0     0.000    52     0.282     1.039
          566.2         0.0      1024.0         0.0        28.9      65536.0       1024.0      56320.0      49387.5    70592.0    69937.9    9408.0    9116.8     85     0.774     0     0.000    54     0.292     1.066
          576.2         0.0      1024.0         0.0        28.9      51200.0       1024.0      70656.0      69867.5    70592.0    69937.9    9408.0    9116.8     85     0.774     0     0.000    54     0.292     1.066
          586.2         0.0      1024.0         0.0        28.9      30720.0       2048.0      91136.0      90347.5    70592.0    69938.6    9408.0    9116.8     85     0.774     0     0.000    54     0.292     1.066
          596.2         0.0      1024.0         0.0        28.9      10240.0       3072.0     111616.0     110827.5    70592.0    69939.1    9408.0    9116.8     85     0.774     0     0.000    54     0.292     1.066
          606.2         0.0      1024.0         0.0        30.8       6144.0          0.0     115712.0      61682.0    70592.0    69941.5    9408.0    9116.8     86     0.779     0     0.000    54     0.292     1.071
          616.2         0.0      1024.0         0.0        30.8       6144.0       1024.0     115712.0      82162.0    70592.0    69966.0    9408.0    9118.4     86     0.779     0     0.000    54     0.292     1.071
          626.2         0.0      1024.0         0.0        30.8       6144.0       2048.0     115712.0     102642.0    70592.0    69968.6    9408.0    9118.4     86     0.779     0     0.000    54     0.292     1.071
          636.2         0.0      1024.0         0.0        44.9      66560.0       1024.0      55296.0      53033.0    70592.0    69977.5    9408.0    9118.4     88     0.795     0     0.000    56     0.302     1.097
          646.2         0.0      1024.0         0.0        44.9      48128.0       2048.0      73728.0      73513.0    70592.0    69978.1    9408.0    9118.4     88     0.795     0     0.000    56     0.302     1.097
          656.2         0.0      1024.0         0.0        44.9      27648.0       2048.0      94208.0      93993.0    70592.0    69978.1    9408.0    9118.4     88     0.795     0     0.000    56     0.302     1.097
          666.2         0.0      1024.0         0.0        44.9       7168.0       3072.0     114688.0     114473.0    70592.0    69978.1    9408.0    9118.4     88     0.795     0     0.000    56     0.302     1.097
          676.3         0.0      1024.0         0.0        41.2       6144.0       1024.0     115712.0      65326.5    70592.0    69980.8    9408.0    9118.4     89     0.800     0     0.000    56     0.302     1.102
          686.3         0.0      1024.0         0.0        41.2       6144.0       2048.0     115712.0      85806.5    70592.0    70005.3    9408.0    9124.6     89     0.800     0     0.000    56     0.302     1.102
          696.3         0.0      1024.0         0.0        41.2       6144.0       3072.0     115712.0     106286.5    70592.0    70006.9    9408.0    9124.6     89     0.800     0     0.000    56     0.302     1.102
          706.3         0.0      1024.0         0.0        44.0      66560.0          0.0      55296.0      46625.5    70592.0    69993.9    9408.0    9122.4     96     0.839     0     0.000    66     0.362     1.201
          716.3         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46662.0    70592.0    69983.9    9408.0    9120.8    106     0.890     0     0.000    86     0.479     1.369
          726.2         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46664.5    70592.0    69988.5    9408.0    9120.8    116     0.946     0     0.000   106     0.588     1.534
          736.2         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46667.0    70592.0    69989.8    9408.0    9120.8    126     0.996     0     0.000   126     0.690     1.687
          746.2         0.0      1024.0         0.0        20.5      66560.0          0.0      55296.0      46674.5    70656.0    69993.5    9408.0    9120.8    136     1.047     0     0.000   147     0.805     1.853
          756.2         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46679.5    70656.0    69993.5    9408.0    9120.8    146     1.096     0     0.000   166     0.904     2.000
          766.2         0.0      1024.0         0.0        16.0      66560.0          0.0      55296.0      46682.0    70656.0    69993.5    9408.0    9120.8    156     1.148     0     0.000   186     1.007     2.155
          776.2         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46689.0    70656.0    69993.5    9408.0    9120.8    166     1.199     0     0.000   207     1.127     2.326
          786.2         0.0      1024.0         0.0        18.0      66560.0          0.0      55296.0      46691.5    70656.0    69993.5    9408.0    9120.8    176     1.247     0     0.000   226     1.226     2.472
          796.2         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46691.5    70656.0    69993.5    9408.0    9120.8    186     1.295     0     0.000   246     1.333     2.628
          806.3         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46696.5    70656.0    69993.5    9408.0    9120.8    196     1.350     0     0.000   266     1.437     2.786
          816.3         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46703.5    70656.0    69993.5    9408.0    9120.8    206     1.402     0     0.000   286     1.542     2.944
          826.3         0.0      1024.0         0.0        16.0      66560.0          0.0      55296.0      46706.0    70656.0    69995.8    9408.0    9120.8    216     1.454     0     0.000   306     1.651     3.106
          836.3         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46713.0    70656.0    70003.6    9408.0    9120.8    226     1.503     0     0.000   326     1.755     3.258
          846.3         0.0      1024.0         0.0        18.0      66560.0          0.0      55296.0      46715.5    70656.0    70006.4    9408.0    9120.8    236     1.552     0     0.000   346     1.866     3.419
          856.3         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46720.0    70656.0    70006.8    9408.0    9120.8    246     1.600     0     0.000   366     1.974     3.573
          866.3         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46725.0    70656.0    70006.8    9408.0    9120.8    256     1.650     0     0.000   387     2.089     3.739
          876.3         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46732.0    70656.0    70010.0    9408.0    9120.8    266     1.699     0     0.000   407     2.191     3.890
          886.2         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46734.5    70656.0    70010.0    9408.0    9120.8    276     1.748     0     0.000   426     2.287     4.034
          896.2         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46741.5    70656.0    70010.0    9408.0    9120.8    286     1.800     0     0.000   447     2.401     4.202
          906.3         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46744.0    70656.0    70010.0    9408.0    9120.8    296     1.853     0     0.000   467     2.510     4.363
          916.3         0.0      1024.0         0.0        29.5      66560.0          0.0      55296.0      46744.0    70656.0    70021.6    9408.0    9122.4    306     1.907     0     0.000   486     2.612     4.519
          926.3         0.0      1024.0         0.0        15.4      66560.0          0.0      55296.0      46768.0    70656.0    70022.2    9408.0    9122.4    316     1.963     0     0.000   506     2.720     4.683
          936.3         0.0      1024.0         0.0        19.5      66560.0          0.0      55296.0      46773.0    70656.0    70023.1    9408.0    9122.4    326     2.016     0     0.000   527     2.837     4.853
          946.3         0.0      1024.0         0.0        17.5      66560.0          0.0      55296.0      46775.5    70656.0    70023.5    9408.0    9122.4    336     2.062     0     0.000   547     2.942     5.004