Edgewall Software

Version 6 (modified by Christian Boos, 13 years ago) ( diff )

start dispatching some of the unsorted items into #Installation and #Configuration sections

Trac and Performance

In the past, Trac garnered a reputation of being a fast web application. This was mainly due to its use of the ClearSilver template engine. Starting with version 0.11, Trac migrated to Genshi, another template engine, much more flexible and powerful in many ways, but also much slower and memory hungry. As the memory usage seems now mostly OK (#6614), there are still many concerns over the performance.

However Genshi is not the only reason for the perceived slowdown, there are several other factors which have to be taken into account when analyzing performance:

  • the increased usage of plugins, each of them can add to the load in subtle ways
  • the new security model of TracFineGrainedPermissions
  • the conditions in which Trac is run (web front-end)
  • the specific configuration settings of Trac used
  • various bugs that might be triggered by any of the above!

In this page we'll try to collect all the various pieces of information related to performance, in order to compile a "checklist" that can be followed when trying to troubleshoot a performance problem, or simply when one wants to get a better performance out of his Trac installation.

Check your installation

If Trac is not installed correctly, performance will suffer.

The most obvious wrong thing to do here is installing Trac as a CGI script. Even for testing, there are better alternatives (tracd).

The second main installation mistake relative to performance would be to serve static resources through Trac. For best performance, they're better served by a web server, see TracCgi#MappingStaticResources

(Note: we should probably move the mapping static resources section to another page, e.g. TracModWSGI)

Other points worth checking:

Check your configuration

Several settings enhance Trac in one way or the other, but have a performance cost, which in some case can be huge.


  • default_daysback set to a high value might induce quite some load, depending on the activity. Pick an appropriate value for your site.
  • the default max_daysback can be inappropriate (e.g. allowing 90 days for a site with lots of activity might be way too much). Don't hesitate to reduce it, especially now that we have paging
  • any setting value than changeset_show_files = 0 can be really expensive, depending on the quantity of changesets to process


  • use of restrict_owner = true can be (very) slow on some installations (see #4245, #8034, #8212 …)


  • repository resync failure which results in a resync attempt for every request - easy to spot in the Trac log (see ticket:7490#comment:36); often due to the "prohibited" MySQL/MyISAM combination (#8067)
  • there was a bug up to 0.11.4 which could cause 100% cpu usage on some platforms (#7785, fixed in 0.11.5)
  • some plugins seem to have a high impact on the performance (read TracDev/Performance/0.11.5)
  • a mis-configured or simply slow mail server make Trac appear very slow (#3220 and numerous others)

See also: TracDev/Performance

Note: See TracWiki for help on using the wiki.