Vsti Development

Hi
Im recently working on vsti development for fun. Now I reached optimisation stage.
And I testing my vst on renoise, tracking cpu usage changes.
And I found something strange, strange cpu usage behavour. I am realy confused…
Becouse Im not very well at programming so help would be very wellcome…

Problem:

Vst sampler. There is very simple sampler loop. Critical function inside loop is hermite interpolation for bouth chanesl (L R).

r=hermite ()
l=hermite ()

Usualy cpu is about 15%.
then I eliminate one chanel cpu

r=hermite ()
l=0.0f;
goes to 14.5%

eliminate both chanels
r=0.0f;
l=0.0f;

cpu usage goes to 8%
WHY CPU IS NOT PROPORTIONAL FOR CHANGES? 15 ->14.5->8% MAYBE ITS STUPID QUASTION,
but somtimes minor and changes in code drasticaly changes cpu usage (but I know that these changes couldnt affect so). And these left 8% cpu is too high for left (without hermite)source code…

sorry bad english (can show the code)
thank for any response

Afraid I can`t help you with technicalities, and if this is renoise specific only taktik may be able to answer.

If it is not renoise specific you may be able to find some help at the kvr dsp forum:

http://www.kvraudio.com/forum/viewforum.php?f=33

HTH

i just found that
cpu usage jums by intervals,
0% 8% 14% 16% 18% …
thats why testing is so wierd
but why it could be cpu usage jums so intervaled…?