Comment by smolder
20 days ago
Usually ones that are written in a slow language, do lots of IO to other webservices or databases in a serial, blocking fashion, maybe don't have proper structure or indices in their DBs, and so on. I have seen some really terribly performing spaghetti web sites, and have experience with them collapsing under scraping load. With a mountain of technical debt in the way it can even be challenging to fix such a thing.
Even if you're doing serial IO on a single thread, I'd expect you should be able to handle hundreds of qps. I'd think a slow language wouldn't be 1000x slower than something like functional scala. It could be slow if you're missing an index, but then I'd expect the thing to barely run for normal users; scraping at 2/s isn't really the issue there.