Windows Interrupts and PL/SQL Developer.

I monitor interrupts on my PC with %SystemRoot%\system32\perfmon.msc.
A ground noise is about 150-180 interrupts/s.
If any program is active then the interrupts increases perhaps a factor of one and a half or two.
If I start PL/SQL Developer then the interrupts increases very strong up to 1100-1200 interrupts/s for all the time the program goes.
But it is not always this case. Sometimes it does not rise.

If I start 2 or 3 instances of PL/SQL Developer (dev, test, prod) then the interrupts rises almost always.

I can't find out wich sort of interrupts this is.

Perhaps it has something to do with teh copy/paste Problem?
Why does the interrupts rise?