cpu % usage decreases when (unrelated) memory usage increases

[Christiaan via Digitalmars-d-learn]

Dear reader,

I have a class X that has a (possibly) heavy array of data S as a 
member. A method f of X makes use of a foreach loop over 
taskPool(some_other_array Y).
The thing is that when I increase the length of S, linux/top 
shows me that my D program only uses 10% of my cpu capacity. This 
percentage varies with the length of S. From my perspective, S 
has nothing to do with X.f. Can someone please explain what might 
be the issue here?

regards, Chris