Why is KMail so memory-hungry?

I've been using KMail for a few years now, and recently upgraded my
OS (Ubuntu) to 9.10. Everything seems to have expanded and in particular
KMail! My poor laptop is only 512MB of real memory and is spending most
of its time thrashing stuff to swap-space. Does KMail load the whole
of my admittedly large collection of old emails into memory? 

I've just spent the whole morning trying to respond to a few emails.
I get long delays - 5 minutes is not unusual just moving a message
from my inbox into another folder. I've just spent the past hour pursuading
KMail to send someone an email - four times it crashed out saying that
the smtp process had unexpectedly died. retrieve the message from the
outbox, null edit, then send again. Eventually it has managed to send it.

I do run a 'busy' machine with Firefox, Open Office, Apache, Mysql all
running together, but they're all part of my normal work and it all worked
fine under Ubuntu 8.04. 

I have been using 'top' to see what is going on, and see that KMail
uses far more real memory than anything else - typical RSS=180m
while other 'large' users are taking around 20m. 

I know that the solution is going to be - 'add more memory' but
I feel that is a cop-out. I'm getting a new laptop for Christmas and
that will get around the current state, but if things carry on expanding
we'll all have to upgrade the hardware more often!

Sorry if this just appears to be a long grumble, but I would appreciate
some positive feedback on why KMail should be so demanding.

Bill
-- 
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| Bill Purvis, Model Engineer           |
|  email: [email protected]                |
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