Performance on big mail folders

[nobody]

My chaotic disorganized inbox consists of multiple
thousands of mails. If I click on a mail, it takes
again ~30 seconds for a response. The courier imap
daemon is at 100% on that server (P4 CPU).

Is it possible to just transfer the mail headers, that
will be displayed on the current page (20 in my case),
or to cache the mail headers for the current session?

[nobody]

Logged In: NO 

Please delete this. I found the enable_cache config entry. :-)