+++ This bug was initially created as a clone of Bug #846921 +++ Non bootstrap addons are registered and loaded from C++ code around http://dxr.mozilla.org/mozilla-central/search?q=LoadExtensionDirectories. It would be nice to measure a time interval for that loading activity as part of the per-addon details recorded in bug 846921
From an email conversation with bsmedberg, > LoadExtensionDirectories would only measure the amount of time it takes to > read and process the .manifest files: it wouldn't tell you anything interesting > about loading, which happens later when the windows are actually opened and the > overlays and whatnot are applied. so unless there's an easy way to capture the time spent applying the overlay, and attribute that back to a specific add-on, we're out of luck. Best bet might be to come up with a more general purpose way of attributing CPU use to add-ons, to include both this sort of start-up work and run time overhead.
Based on discussions with bsmedberg and experience with telemetry for bootstrap add-on start up, this is unlikely to give us any useful information.