Hey there! Jacob, Frontend leads here. At GitLab we've put together a team of 5 Frontend Engineers (including myself) to focus solely on performance and stability issues. We are focusing on reducing the size of our JS and CSS. We are currently focusing on splitting our one giant JS file into many smaller JS files. Here's our current issue for code splitting the JS. https://gitlab.com/gitlab-org/gitlab-ce/issues/41341
What real-world speedup will you see? There's no data in that issue to support the idea that this is worth doing. Surely someone hacked up a split version and ran some benchmarks, right? Maybe you could include that data somewhere as the closest thing to that I can find is:
> Benefits: We will have files separated. It’s going to be better.
I'll add our benchmarks into that issue shortly.
Our biggest slowdowns are parsing, layouts, and memory. Without this splitting every file is imported, functions are instantiated but not used. With our new method only files needed are bundled and most of the dispatcher.js file is removed. Removing error prone string matching from switch statements to having it automatically done by webpack.
The plan is:
1. Split up the files.
2. Get rid of the as much of the dispatcher.js as we can and have web pack do the routing dynamically. That would eliminate most of 1 large confusing file (dispatcher.js). JS is still cached for the pages you visit but it isn't 1.5mb of JS it would be ~20kb of JS.
More generally, tuning the runner's polling interval to minimize latency is also tricky, especially with multiple independent runners, and the runner doesn't handle 429s well in my experience (getting stuck in a tight retry loop without backing off sensibly, thus continuing to exceed its request limit).
Here is a link to our current CSS Refactor plan which will reduce the size of our CSS significantly and reduce render times. https://gitlab.com/gitlab-org/gitlab-ce/issues/42325.
We've got a lot in the pipeline. In the process we won't be shipping any new features, unless you call blazing speed a feature.