ProFTPd and KDE

[crystall]

Hi everybody, I am experiencing a weird performance problem. I've got a Gentoo box with ProFTPd on by default serving as a file server for my LAN which is also used pretty often as a desktop machine. I noticed that when KDE is running the speed at which I can download/upload files from the machine drops significantly but I don't understand why. Usually I get 11 MB/s of transfer speed to the machine (I'm on a 100Mbit LAN), but when KDE is running it drops to 1-2 MB/s at most. If I use IceWM I do not experience the same slowdown but when KDE is on even if no other app is running I cannot push it past 2,5 MB/s. If I run 'top' during an FTP transfer I can see the wait time skyrocket to 95% with 0% idle time. The whole thing is pretty weird. I am using the latest stable versions of KDE and ProFTPd on an x86 machine, the kernel is the latest stable 2.6.9 (I am not using 2.6.10 because it proved unstable on my machine, dunno why). The ethernet card is a 10/100 Via Rhine II integrated in the southbridge.