docs: Performance checklist

[felixrieseberg]

Description of Change

This PR introduces a performance checklist. It's a bit self-documenting, but I'd like to highlight that it's not meant to be prescriptive or exhaustive.

For internal discussion, see #proj-performance-docs.

Checklist

• PR description included and stakeholders cc'd
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Added a performance checklist

[PalmerAL]

This seems fairly comprehensive, and it covers a lot of the things I've run into in the past. A few more things that it might make sense to add:

• Even if your app shares code with your website, you should bundle resources in your app rather than loading them over HTTP.
• In most cases, it's better to bundle your code together rather than trying to require() everything on startup.
• I know you mentioned it already, but it might be a good idea to emphasize more just how slow remote is, since it's one of the largest Electron-specific sources of slowness.
• Minimizing resource usage when the app is running in the background.

It might also be interesting to talk about the differences in user expectations between a website and a desktop app. I think most people have gotten used to websites being somewhat slow, but don't have the same expectations for desktop apps, so if you're working with Electron for the first time, you may need to focus on performance more than you would in the past.

[MarshallOfSound]

Even if your app shares code with your website, you should bundle resources in your app rather than loading them over HTTP.

I wouldn't recommend this this point blank. There are significant cons to this, namely version drift and the fact that updating your website now means you have to update your app as well. Their are significant pros and cons to live-loading and shipping in-app and I don't think we can recommend one without a comprehensive list of those pros and cons which I don't think belongs in this document.

In most cases, it's better to bundle your code together rather than trying to require() everything on startup.

👍 Especially on windows, file system ops are slow ™️

Minimizing resource usage when the app is running in the background.

Mentioning putting things into requestAnimationFrame or checking document.visibilityState might be good here

[issacgerges]

Really great stuff @felixrieseberg! This is going to make a massive impact. Just some stuff that comes to mind when reading:

• My number one tool for demonstrating the cost of work in the main process has been Johannes' fiddle. Curious if it would be worth including examples like this one when it makes sense https://twitter.com/johannesrieken/status/1086311961128620032

• Love the warning around remote, but I wonder if remote.getGlobal deserves special attention. I think people rarely understand the performance trade-off there, partly because the API hides a lot of the complexity around this almost magic front. I think it may be hard for people to understand that calls like remote.getGlobal('settings').getTheme().topBar.color is around 10 ipc messages back and forth.

• For unnecessary polyfills, it might be worthwhile to mention that electron is a valid target as a browserlist and can be used with @babel/preset-env

• It's well documented, but I wonder if the Measure, Measure, Measure section deserves to link out to https://electronjs.org/docs/tutorial/debugging-main-process.

• Should devtron be called out? Might be some overlap with the require graph / ipc stuff and some of what you've called out here.

[Kilian]

1 through 6 are titled as things you should not do, 7 is something you should do. Combined with "attempt these steps" above, it seems like all things you should do, so maybe rewrite the intro line to:

Chances are that your app could be a little leaner, faster, and generally less 
resource-hungry if you review the following checks.

Or change the titles of 1 through 6 to be the thing you should do, which is mostly adding "Don't" in front of the current titles.

[malept]

This is great! My comments are mostly grammatical / formatting.

[release-clerk]

Release Notes Persisted

Added a performance checklist

[malept]

This needs to go into the 7-0-x branch for it to be deployed to the website, right? (Ignoring the fact that it's not in the docs index page yet...)

[miniak]

/trop run backport-to 8-x-y

[trop]

The backport process for this PR has been manually initiated,
sending your 1's and 0's to "8-x-y" here we go! :D

[trop]

I was unable to backport this PR to "8-x-y" cleanly;
you will need to perform this backport manually.

[miniak]

/trop run backport-to 7-0-x

[trop]

The backport process for this PR has been manually initiated,
sending your 1's and 0's to "7-0-x" here we go! :D

[trop]

I have automatically backported this PR to "7-0-x", please check out #20757