linux-2.6.23 - acting funny

[poison]

Hi :)
I have two harddisks with encfs on top of reiserfs between which I could copy 
data at ~22MB/s before the upgrade from 2.6.22 to 2.6.23. 
After the upgrade the transfer rate stuck at ~14MB/s and changing nice values 
did not help anything.

And now the funny part: 
I noticed the transfer rate go up to ~20MB/s when I startet compiling stuff. 
I just need to run a CPU hog like:
  while true; do echo test > /dev/null; done
and the transfer rate jumps from ~14MB/s to ~20MB/s.

top shows the two encfs processes with ~30%(read) and 50%(write) CPU usage no 
matter if I run the CPU hog or not.

Could this eventually be due to the new scheduler? Do I need to tune anything?

System: E6600, 4GB RAM, Slackware 12, config attached.
Do you need anything else?

PS: please CC me, I'm not subscribed

Attachment: config.gz
Description: GNU Zip compressed data