WPMU Performance assistance w cluster/load balancer

We run WordPressMU 2.6.1 in a cluster of Solaris servers behind a load balancer. At present, we've got 700+ users and ~470 blogs (~350 active--others are test/abandoned).

I've made a plea for tips running WPMU in cluster behind a load balancer on the WPMU Forums, but haven't gotten any assistance as of yet (we're still hoping ...

Here're our specs:

  • Apache httpd 2.2.8
  • MySQL 5.0.51a
  • PHP 5.2.5

MU-Plugins:

Plugins:

We're considering running WP Widget Cache, as well as Multi-DB.

We're running 3 custom themes, which use a proprietary plugin to provide configuration values for analytics, ads, etc.