Performance issues.. one is a linux kernel bug

Using claws myself (and seeing it crash 4 times a day since the last update), I used
latencytop to diagnose one of the performance issues with it... and it's a kernel bug.

Short term solution:
echo 4096 > /sys/block/sda/queue/nr_requests
and suddenly all is happy

longer explenation: claws maildir support causes many inode updates, which in turn causes many
IOs. The block layer does CFQ fairness at a low level, but these IO's don't get there (they
get blocked waiting for requests), and the request layer is not fair... stalling claws for 2+
seconds at a time