In gmane.comp.lang.smalltalk.squeak.general Andreas Raab <andreas.raab at gmx.de> wrote:

> 1) Time millisecondClockValue and its use of gettimeofday. It turns out 
> that in our settings, Time millisecondClockValue takes about 10% total 
> execution time (we use it for measuring throughput so it does get called 
> *a lot*). We will work around this by adding a low-res clock that gets 
> updated without calling gettimeofday but it was interesting to notice 
> how much time goes into that.

For discussion on that topic, there might be some input in this thread ;-)

http://lists.squeakfoundation.org/pipermail/squeak-dev/2002-February/034747.html