Textpattern Support Forum

Depends entirely on the plugin. Each plugin takes a different task and has its own cost as far as server resources go. Plugins that do heavy lifting and processing can have bigger impact.

In general, for instance plugins that merely just introduce new Textpattern markup tags have no impact at all until the plugin’s tags are used. On pages where the tags are not present, the plugin is literally in sleep and has no visible impact at all.

Just installing plugins does not have major impact to performance. The fact that it’s a plugin, doesn’t make so that it has bigger impact than having the same code built-in the core.