slow sql in xpcshell testing

One of the best things about performance monitoring is that it sometimes shows up problems in very unexpected areas.  Yesterday while working on some improvements to telemetry, I noticed that the telemetry packets being sent had information for slowSQLStartup.  That is, there were some SQL queries (4 of them, to be exact; 3 unique queries) that were taking more than 150 ms to run just during xpcshell testing.

These queries were run by the addons manager and already have a bug on file.

I’m guessing that this slow SQL does not occur during all xpcshell tests, but only those that create a profile (about 5% of tests). which would translate into ~1% of xpcshell testing time.  Still, speedups are speedups, and fixing these queries would be a good speedup for Firefox users generally.

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