Safari and Macmail Slow Launching?

In the last few days both Safari and MacMail have taken up to thirty seconds to launch. Before this neither took more than about five seconds.

Anyone got any ideas as to why this might be?

Things I've tried so far are:

Resetting Safari
Clearing out caches using CacheOutX
Checking preference files using Preferential Treatment (all fine apparently)
Manually running all three sudo maintenance scripts
Checking file permissions using Disk Utility (again, all repaired apparently)
Doing a Safe Boot
Running VirusBarrierX scan (no virus detected)
Checking disk S.M.A.R.T status (verified)

None of the above has made any difference. The disk is an 80GB drive with around 34GB of free space so there shouldn't be any fragmentation issues.

Any ideas anyone?