In order to diagnose save timing problems much more quickly, it would help to have some breakdowns by component/extension (e.g. FlaggedRevs, Echo). This could go beyond save timing, but should be segregated by entry point (save, upload, login,...). Save timing would be a good start in any case. The idea would be to easily spot large increases in runtime attributed to some module so that an appropriate maintainer can be notified and RelEng can have an easy idea sometimes of what to revert. Right now this is very difficult.
Perhaps we can have per-wiki breakdowns for the top wikis.
A related concern is having leaderboards for template and Lua modules...but that's another task itself.