I recently bought an Athlon motherboard with a builtin Realtek 8139 
ethernet chip (Yeah, I knew realtek chips were bad, and didn't base my 
decision on that; it was basically a "gimmee"). Last night I was ripping a 
bunch of new CDs onto an NFS-mounted drive on another machine and happened 
to look at "systat vmstat" output and noticed that the machine was 
spending >65% of CPU time in interrupt code! (and this is on an Athlon XP 
1800+). I turned off the machine, plugged in a spare Intel 82559-based 
ethernet card and restarted - interrupt CPU usage dropped down to 2%!

I understand that Realtek chips are bad, but are they really *this bad*! 
What is it in ~1000 interrupts per second that can use up 65% of an Athlon 
XP 1800+?

I'm using -current as of about 10 days ago.