Issue with Search

[MacHack]

This is the second time this has happened and I am not sure what I can do to fix/prevent this.

Ever since upgraded to 4.0 the forum runs fine then we see a huge slow down in the time it takes for posts to go through once "post reply" is clicked. When I go to repair/optimize the database it would hang at the search db elements. The last time I emptied the search index and then was able to repair/optimize the database. The site ran slow only when replying, searching and deleting posts would take up to a minute to process.

I am assuming that this is all related to the search index being corrupt. Last time around after about 4 days it just started working again and things were back to normal and I was able to rebuild the search index. Now 2 months later it has happened again and I cleared the search index and it is 5 days later and doesn't seem to have "fixed" itself. Our host says there is no problem on their end and vbulletin seems to work fine for the most part, just when posting/searching/deleting there is a major lag. Any help anyone can offer would be most appreciated.

We are currently running 4.0.5 and I am looking to do the upgrade this weekend. I am pretty sure the first time it happened we were on 4.0.3 as I remember doing an upgrade right after the first time it happened. This is the first time any major issue has happened in the 2 years of running a vbulletin site.

[MacHack]

Last night the forum seemed back to normal so I rebuilt the search index and the problem came right back. I dropped the search tables and repaired/optimized the database and went ahead and upgrade to 4.0.7. I haven't rebuilt the search index but I am still getting extremely slow results when posting, deleting or clicking "new Posts" even after the upgrade.

Any help would be greatly appreciated.