I have noticed that my particular instance of Trac is not running quickly and has big lags.  This is at the very onset of a project, so not much is in Trac (except for plugins and code loaded into SVN).
Setup Info: This is via a SELinux system hosted by WebFaction.  It is behind Apache, and connections are over SSL.  Currently the .htpasswd file is what I use to control access.
Are there any recommend ways to improve the performance of Trac?
We've had the best luck with FastCGI.  Another critical factor was to only use https for authentication but use http for all other traffic -- I was really surprised how much that made a difference.
How to improve Trac's performance