Forum Serious Performance Issues - Vbulletin 4.2
 

Hello everyone! Having some performance issues with our Vbulletin site. We have about 3,000 registered users and about 2,000 active members. Never more than 1,000 on at any time.

We upgraded our hosting from an entry level VPS(1 CPU, 750mb) and things have gone seriously downhill. The tier to which we upgraded gave us 1750mb of memory and 1 CPU. I did a live upgrade and while performance degraded during the upgrade, I chalked it up as due to the upgrade. Well, the upgrade finished and performance never returned to normal. Our CPU utilization quickly spiked through the roof and was obviously handicapping us.

I spoke with our hosting support for quite some time and they convinced me that we had removed our memory bottleneck, only to uncover a CPU bottleneck. To me, this seemed plausible. Well, I upgraded our server again. Currently, we are on a 2 CPU, 3500mb VPS. Things seem to have only gotten worse. Load returns to normal levels only late at night/early morning when we have no users online.

In checking our processes, the biggest memory hog is the showthread.php service. I have an extremely hard time believing what I'm seeing from our server information data.

Can you all help me here? Why would an upgrade cause our performance to degrade so severely? Why would every usage category spike(server load, memory usage, active processes, total processes)? The bandwidth used has even gone up by 200%! The thing that is so baffling to me is that our site ran perfectly on the entry level VPS(1 CPU, 750mb.) Our hosts are saying it isn't their fault, and I'm saying it isn't my fault. There have been no huge influxes of users, no significant traffic events, nothing out of the ordinary at all!

First upgrade done on 1/22 in the evening. Second upgrade done on 1/23 in the morning. EST time

http://i49.tinypic.com/344bm2u.png - Load Average 2 weeks
http://i48.tinypic.com/sfkt8y.png - Bandwidth Average Month
http://i46.tinypic.com/5v3g7.png - Ram Usage 2 Weeks
http://i46.tinypic.com/sfdz4n.png - Active Process 2 weeks
http://i47.tinypic.com/11ltr1z.png - ACtive Process 2 weeks

I'm at my wit's end here guys. Any help would be appreciated. Including: What to ask our hosts, what I should change on my end, etc..

Thanks for your time!