for several days I tried to figure this out by myself, but I can't. I'm about to change to Thunderbird, but it won't be possible anyway.
What happens:
Whenever I start kontact, as soon as I hit one mail in order to view it, it slows down dramatically to the extent, that it is impossible to work with it.
It takes a few seconds until the contents of that mail becomes visible. Then clicking on the next mail, it just sits there, doing nothing for half a minute or more.Eventually, it will highlight that message, but the contents isn't shown for another minute or more.
I have tried removing the kontactrc, but that didn't change a thing. I also tried removing the kmailrc (which I usually wouldn't want to do, as the amount of individual settings in there is tremendous), no change.
The Sysguard shows activity in kontact,up to a certain level, when several kio_pop3 (in total five) and kio_file (in total three) processes are opened (filtered by "kontact"). Then, the activity stops (no cpu usage, no increase in RAM usage, which remains at a relatively low level), and I can't access Kontact any more. It just gives me a grey screen.
I use OpenSuse 11.1 64-bit and KDE 4.3.1, my machine has 8 GB of RAM and an Athlon 64 X2 5200+.

Any idea what I could do? I use KMail heavily, and people rely on my quick responses.