I have the following workflow:

• opening vim
• enabling visual line mode with shift-v, selecting lines, then y to yank those
  • I get a message “151 lines yanked” or something like this
• closing vim, immediately opening another vim
• pasting selected lines with p
  • only half of the previously copied lines are inserted !

Does anyone know what happens ?

Is there a problem with my workflow ?

I find it very practical sometimes to do like this.