I'm planning on adding Redis support soon enough so that sudden spikes would have little impact on the database server (which is nearly always the bottleneck, unless you're compute-intensive, which isn't the case with Commento). So that if you suddenly get a few hundred thousand visitors, most API responses are cached and only a fraction will actually require disk access. Like reddit does, where it'll temporarily say there N comments, but when you open the page, there wouldn't be that many. A few seconds of inconsistency is a fine compromise in the comments world. Of course, Redis isn't going to magically make everything faster, so I'll have to be careful with where I introduce it. Optimise for the common case and all that.

I'm still in uni, and I've never actually worked on large-throughput, high-scalability stuff before, so all this has been a great learning experience for me. If you have any suggestions or war stories that might be relevant, I'm all ears!

And also, very well done! Your software seems to work very fine, a lot of thought already went into scaling and general stability of the backend. And for me, as fullstack working for a design company, your website layout and design is pretty good. If you didn't have help with that, kudos to you, good work, especially for someone still in college :)

Edit: Website performs pretty good in a Lighthouse audit, apart from Accessibility features.