The only reason they take up more resources than necessary is that the default VM settings are bad. They use an older GC algorithm with very low RAM setting, but all it does is make the GC run much more than it would with a decent size.

If you happen to try it out again, I recommend setting the heap size to at least 4GB and removing the obsolete GC setting (defaulting to the G1 collector) or even better, changing to ZGC. Hopefully they will fix it in a newer version soon.