Improve start-up performance

[planger]

This is an umbrella issue for coordinating different work streams to improve the start-up performance of Theia, both for Electron and Browser deployment. At the moment, the following topics / PRs are work in progress:

• Gathering of measurements
  • Capture stopwatch results #12812 and make them available via /metrics
  • Run end-to-end tests periodically and create a report showing how the measurements evolve over time (see also https://github.com/eclipse-theia/theia-e2e-test-suite)
  • Extend the end-to-end tests above to also run with Electron (blocked by Basic playwright electron support #12207)
  • For production builds the performance logging is broken as it relies on the class names. We should at least document how to disable class name optimization in webpack.
• Backend improvements
  • Between v1.38 and v1.40 the backend start-up has improved impressively by > 50 % (largely enabled by the backend bundling)
  • Defer i18n initialization [perf] Load localizations lazily #12932 (see also kittaakos/arduino-ide@b788005)
• Frontend improvements
  • Reducing awaits in the frontend seem to enable a performance gain of ~400-1000ms of about 2500ms startup overall (see Improve frontend startup performance #12936)
• VS Code Extensions
  • First measurements indicate that interpreting some declarative API is rather slow, but this needs to be confirmed
  • Don't await plugin deployment in backend process Don't await plugin deployment in backend process #13134
• Electron
  • Open initial electron window early and reuse it later #12897
• Packaging
  • Moving to ESM modules could lead to smaller bundle sizes, thus improving load timesL Build Theia as ESM modules #13272
    Please feel free to add your topics or comment on any of the lsited streams of work. The goal of this GH issue is to collect and coordinate the work towards performance improvements of several teams.

[sdirix]

There are two related issues listed in the old epic #9869 which could be added to the list here:

• Add performance measurement #9722
• Plugin deployment slows down Theia frontend startup time #9868