Running Wordpress 3.1.2 (newly updated, installed as 3.0 about a year ago) with subdomain multisite & using the Sunrise domain mapping plugin.
The frontend is fast, the backend (wp-admin) is very slow on the network admin site (www.example.com/wp-admin) but runs at "normal speed" on one of the subdomain backends (foo.example.com/wp-admin).
The server is our own, Ubuntu 10.04 with mod_security (which I've heard can slow things down).
Is there anything I can do to speed up the backend or run a trace somehow?