I didn't really feel like writing this, but off the top of my head:
webgl performance:
- besides the fact that it's well known that WebGL performs pretty terribly
- 3 different types of compression/or not: gzip, brotli, uncompressed
- which one do you use? some don't always load
- each browser varies completely (especially from webgl 1 to 2), and safari usually being the worst of it
- on that note, there's usually different issues on a mac vs a windows machine
- monitoring performance in the browser is also extremely sketchy, so much more overhead, and tricky to look at (not very many people know how to review this information either)
asset management:
- zipping assets for indexeddb, no guarantee how these are loaded, when they're getting cleared
- limited resources for large games, indexeddb has a cap on it as well that varies from device to device
other problems:
- memory issues, as soon as you run out of memory in webgl it throws up a generic error that's incredibly hard to get debug...which leads me to...
- debugging. adding deobfuscated logs (full stack traces) is pretty much the only way to view it, from console, and cannot properly be connected to a debugger. going line by line through webasm is again, extremely painful, and to be blunt...it's outdated. this is 2023, we have way more robust ways of building games to deal with these problems.