400+ Forums on 1 vBulletin setup lags on a server.
 

Hello.

I have a vbulletin forum with 400+ forums on a server with specs:
Code:
AMD Athlon 64 X2 6000+ Dual Core
8 GB DDR2
2 x 750 GB SATA II
At last month we start lagging* after some profiling* i found that create_forum_bit(-1) calls over for 1 second and makes CPU Load ~48-68%.
We are using eAccelerator & Memcached as caching/performance tools.

What you can advise* to fix this lags(except deleting forums) ?

P.S. Memory usage is very low* lags only parsing/creating forum's bits.