I have kmail 1.13.2 running with KDE 4.4.2. Recently (for about two weeks) the
performance has been really dreadful. It routinely drives the load average on
the system to about 1.4 or 1.5, takes up about 90% of a cpu and generally
makes the whole system only marginally useful. I can easily use webmail to
communicate but that's not why IO have Kmail installed. I don't know what bits
are responsible for this behavior and don't know where to start looking. This
seems (as I recall) to have started with the KDE 4.4.0 release and has been
rather sliding since then. I use maildir format mailboxes and there has been
no sudden increase in the number of emails I get or send. If I let kmail alone
for a few hours it gets somewhat better. I suspect an indexing program, I
suppose akonadi? or nepomuk? I seem to have 8 instances of nepomuk running.
Where should I be looking for clues?