1. As far as "performance", you definitely want to profile your app for any "hot spots" or bottlenecks.
I presume you used GNU cc. Here's a good tutorial on using the GNU profiler:
2. Don't give too much credence to the timings you get back from gettimeofday(). Just because it returns values to the microsecond, that doesn't necessarily mean that those values are *accurate* to the microsecond.
Generally, the smallest unit of granularity I'd have much confidence in is
down to the millisecond (*not* microsecond!).
'Hope that helps .. PSM