[meta] All page load bundle must be under 100kB

[tylersmalley]

One of our goals is to keep Kibana fast. A large part of this is to reduce the amount of Javascript that is downloaded and parsed on each page load. We have for some time provided bundle size metrics on pull requests. From the docs:

The size of the entry file produced for each bundle/plugin. This file is always loaded on every page load, so it should be as small as possible. To reduce this metric you can put any code that isn’t necessary on every page load behind an async import().

Code that is shared statically with other plugins will contribute to the page load bundle size of that plugin. This includes exports from the public/index.ts file and any file referenced by the extraPublicDirs manifest property.

Since these files are loaded on every page load, it's important to keep this size to minimum. We have documentation to assist with reducing these bundle sizes through code splitting.

Here are some examples of plugins implementing code-splitting:

• Kibana App plugins
  • Reduce visTypeTimeseries bundle size #64631
  • Reduce visTypeMarkdown bundle size #64638
  • Reduce visTypeVega bundle size #64749
  • Reduce lens bundle size #64769
  • Reduce visTypeTable bundle size #64778
• Security & Spaces plugins Reduce security & spaces plugin bundle sizes #64192
• Maps plugin Reduce maps bundle size (code splitting) #64317
• Uptime Reduce uptime bundle size #65257

While we do have the limits.yml, we would like to institute a ceiling of 100k and in order to accomplish this, we need all plugins to get under that limit.

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[mshustov]

Let's update limit values https://github.com/elastic/kibana/blob/master/packages/kbn-optimizer/limits.yml at the part of this issue. There are some numbers outdated there.

[tylersmalley]

@danielmitterdorfer this is probably something we want to move to the performance working group and could use some help pushing. This is really something that ALL web applications deal with and something that should be no different for anyone developing plugins in Kibana. 100kB is really just the bare minimum considering there is 160+ plugins.

[lizozom]

@tylersmalley and @danielmitterdorfer
I've merged PRs from this issue into #88678
I'm closing this issue and we can continue any related conversations there.

On a side note, I do think that we need to justify and prove whether bundle splitting is a good strategy in the long term in our performance tests.