Tools to analyse/share startup performance

[jrieken]

• https://github.com/jrieken/node-fs-monitor
• log app-ready event
• include all loader stats when running with --performance

[jrieken]

@bpasero FYI I have split the "[main] start => window.loadUrl()" perf-counter into two counters which are "[main] start => app.isReady" and "[main] app.isReady => window.loadUrl()". I have seen the former, which signals that electron is now ready, to be very slow on windows.

@seanmcbreen I have checked and don't think we were having any telemetry queries running on ellapsedWindowLoad which would now see shorter times. I think it would be interesting to check what the newly perf-counter ellapsedAppReady is telling us

[jrieken]

To verify start code with the --performance flag, show startup perf, and make sure the app-ready event is logged and that there dedicated stats about the loader, like load script and script eval