Having a very large Trash folder (e.g. 1/4 GB) can slow down evolution
considerably.
All messages go to trash when deleted. The default option is not to
empty the trash automatically as evolution closes.
When noticing that performance of evolution has fallen, the trash folder
isn't an obvious place to look (especially if you've never looked in
there before). For quite a while, I'd put the poor performance down to
either the code for threaded message display being slow; or degredation
in performace which has gradually been introduced in updated versions.

I have posted to the Debian BTS as Debian developers (or more
specifically followers of debian-devel mailing lists) are likely to
suffer the most from this.

Possible solutions:
* Give additional options for emptying of Trash:
	'Purge mail when it is more than X days old.'
	AND have this as default.
* Issue a warning when the Trash folder exceeds a certain size.

This issue also affects the sent mail folder as it too is auto
generated.