Open Bug 1360253 Opened 3 years ago Updated 2 years ago
Use lazy Migration
Utils getter and stop using Preferences .jsm from Auto Migrate .jsm
Per bug 1329712 comment #2: (In reply to Florian Quèze [:florian] [:flo] from comment #3) > (In reply to :Gijs from comment #2) > > I should really just have removed this in bug 1285577, but it got missed, > > and then I forgot I'd filed this. But AIUI we can now just request this > > module when we need it (usually only in startup migration, or when we're > > showing the relevant "did you want to undo this thing" notifications from > > about:home or about:newtab). > > > > Given that about:home and about:newtab still load this, it's possible > > there's more of a perf gain to be had by making that code conditional on > > automigration being enabled and/or lazy-ifying e.g. the MigrationUtils > > import (which isn't necessary to just check if we're going to show the > > notification in the common case that we won't show it). > > > > Florian, is that worth pursuing in a separate bug? Don't know if you've > > already noticed this in startup profiling or no. > > Here is what I have in my existing startup profiles: > > Mac: https://perfht.ml/2pltLPZ Loading AutoMigrate.jsm takes 3ms, and from > the profile I would be tempted to say removing Preferences.jsm from that > module (or at least from the _checkIfEnabled method) may be a good idea; but > 1ms is just one sample, so can't say for sure. > > Windows: https://perfht.ml/2plmtfc Loading AutoMigrate.jsm is visible but > just 1ms, so not really significant. > > I should have access to a reference device soon, so I'll have more detailed > profiles. > > If it's easy, lazy-ifying MigrationUtils would still be a good idea: it > doesn't seem to be expensive in time (all the modules it imports are > lazy-loaded), but would still save some memory. Lazy-ifying the getter and stopping use of Preferences.jsm seems straightforward, so let's at least get that bug on file.
Priority: -- → P3
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