Panelizer triggers CTools file scans for finding all plugins on all panelized pages

Panelizer implements hook_admin_paths(), which is run everywhere and all the time, and hook_default_page_manager_handlers(), which is run for page manager controlled pages, and delegates this to all plugins. This will fetch all available plugins by using ctools_plugin_load_includes(), and that function only caches when you request a particular file.

This results in some disk IO and unnecessary cache writes, which is not very good for performance.

I don't know a good solution for this, but here are some ideas:

A) Change ctools_plugin_load_includes in CTools so that it caches even if you don't specify a file that should be loaded. This will impact various administration UI:s, since that would require a cache purge before any change is picked up. We could potentially add a parameter to the function, $bypass_cache or similar, if we want to bypass the cache for admin tasks, but this would still be a fair amount of re factoring to get that in everywhere it's used. If we want to go this route we should obviously move this to CTools.

B) Put a cache layer inside of panelizer. This will fix the problems, but it will also result in duplicate cache entries for the same thing, and CTools is meant to handle this thing already, but it will solve the immediate problem.