It partially depends on the scenario.
Lots of monsters cause load for various reasons that can probably be improved.
Fire is improved but it’s still a naive cellular automata simulation that checks its surroundings a LOT so it’s pretty expensive.
Scent diffusion is under control, but if it were improved by a lot it would enable some additional features (different monster groups having scents, which the player could detect).
FoV (Field of View) and lighting are still pretty expensive, and are going to get worse with 3D maps enabled.
Mapgen has several corner cases where it locks the system for up to a minute generating things, the most obvious of which is when it spawns a large number of vehicles on top of each other.
The bulk of game startup time is spent loading json files, which could be a lot faster.
There are some places where animation delays cause pauses, but that’s not a performance thing, it’s literally sleeping to make animations happen.
In tiles mode, tile lookup has grown a bunch of different fallbacks which is contributing to general slowness there.
A note on performance work though, if you don’t fire up a profiler or write a timing benchmark to verify your results, I don’t want you making performance-based pull requests. If it’s not verified it’s just guesswork.
