[personZ]

Unless you used a specialized, customized version of netsend, yes it was rate limited -- it by default waits on the clock interval, and warns you if you try to call it in defiance of that. Further it is endlessly calculating the time and calling system functions to get the time.

As a test of max throughput, it is a horrible test. I don't have the motivation to prove it, but I would be surprised if more than 5% of the CPU load actually went towards networking, the rest time calculations and interval tests.