Unless you have something like high throughput real time processing going on a few milliseconds here and there will make no difference at all. It is far more important to write concise and easily maintainable source code than it will ever be to shave .001% off a program's run time.
These are elaborations that take a long time, sometimes even 30 minutes (depends...).
Rewriting some functions, I was able to reduce the processing time from 5 to 20 times, it means that in the best case I got a time to wait for the result of about 90 seconds instead of 30 minutes.
Anyway, I will take your advice.
