When I compile around 1700 files using make -j, it takes 13 minutes on an 8-core PC with 100% CPU load, whereas on a 56-core server, it takes 7 minutes but with only 10% CPU load.

Use MINGW64, PowerShell, CMD, all the same result.

This is my makefile target and command section fragment：

#######################################
# build the application
#######################################
all: all-build
    @( 
        tTime=$$(($$(date +%s) - $(START_TIME))); 
        if [ $$tTime -lt 60 ]; then 
            echo "Build Finished (took $$(($$tTime))s)"; 
        else 
            echo "Build Finished (took $$(($$tTime / 60))m:$$(($$tTime % 60))s)"; 
        fi 
    )
    @echo ' '

all-build:
    $(MAKE) -f $(THIS_MAKEFILE) --no-print-directory $(BUILD_DIR)/$(TARGET)

$(BUILD_DIR)/$(TARGET_BASENAME).elf: $(BUILD_DIR)/ld.args
    @mkdir -p $(@D)
    @echo '[LD]: $@'
    $(CC) "@$(BUILD_DIR)/ld.args" -o $@
    @echo 'Finished building target: $@'
    @echo ' '
ifneq (, $(DST_DIR))
ifneq (, $(DST_JSON))
    $(MAKE) -f $(THIS_MAKEFILE) --no-print-directory post-build-elf
endif
endif
    @echo '[SZ]: $@'
    $(SZ) --format=berkeley $@
    @echo ' '

$(BUILD_DIR)/%.o: $(CURDIR)/%.c $(BUILD_DIR)/cc.args
    @mkdir -p $(@D)
    @echo '[CC]: $<'
    $(CC) "@$(BUILD_DIR)/cc.args" -MD -o "$@" "$<"
    @echo 'Finished building: $<'
    @echo ' '

$(BUILD_DIR)/%.o: $(CURDIR)/%.s $(BUILD_DIR)/as.args
    @mkdir -p $(@D)
    @echo '[AS]: $<'
    $(CC) "@$(BUILD_DIR)/as.args" -o "$@" "$<"
    @echo 'Finished building: $<'
    @echo ' '

$(BUILD_DIR):
    @mkdir -p $@

post-build-elf:
ifneq ($(CC_BIN), ccarm)
    $(dir $(CURDIR)/$(THIS_MAKEFILE))/PostBuild.bat 
    $(DST_DIR) $(DST_JSON) $(BUILD_DIR)/ $(TARGET_BASENAME) $(CC_PATH) $(PREFIX) $(user_postbuild) $(arg_postbuild)
else
    $(dir $(CURDIR)/$(THIS_MAKEFILE))/PostBuild.bat 
    $(DST_DIR) $(DST_JSON) $(BUILD_DIR)/ $(TARGET_BASENAME) $(CC_PATH_s32k3xx_gcc) $(PREFIX) $(user_postbuild) $(arg_postbuild)
endif
    @echo ' '

8-core PC cpu load

56-core server cpu load