Slow bug report / update submission

[ArKay]

We just upgraded from Mantis 0.x (can't remember) to 1.0.2. Every time we report or update a bug it takes about 20-30 seconds until the submission went through and the user gets to the overview. The mail gets send right away using SMTP on the same host (arrives within a second, I'm using IMAP) so that shouldn't be the problem.

I tried enabling the SQL statement tracking function but those only show which statements got executed to build up the current page. So after submission I only see those queries used to build the bug overview, those are all rather fast.

Any ideas what could be causing this or where I could look?