Linux server tickrates.

[HbG]

I noticed when playing on our linux servers the tickrate isn't what it should 
be (the default of 20) at any time. Usually between the minimal tickrate of 5, 
and approximately 16 at max. Increasing the tickrate to 25 gets me 20 at max. 
If the server fills, tickrate drops to 15 (with a setting of 25), also it 
doesn't seem to be as constant as in  2K. This is NOT a cpu issue, usage is at 
that point still well below 100%.

In win2k it all works fine (running ded and client on the same cpu, high 
priority for the server).

I know linux UT servers had lower tickrates then their windows counterparts, 
but it seems like more is going on here. Anyone can confirm this?