Any idea how this mod effects performance in large battles?

There shouldn't be very heavy significant performance impacts as far as I've tested in various scenarios, from vanilla to said mods in the information section. This mod only tracks entities that are damaged and on top of a tile so it's fairly lightweight.

I'm pretty sure this mod combined with Space Exploration's Coronal Mass Ejections has a pretty hefty impact. Game slows to a crawl and Stable Foundation's tick time skyrockets.

Any sort of fast, large area DoT (damage over time) on structures will likely have some performance issues since default values on checking entity health are about 1/10th of a second. You can adjust the entity check value to a second or every couple of seconds to alleviate the slowdowns.

I'm already using on_damaged events as to not have to iterate through every entity in existence and check health. I've also considered removing tick checking, but it has some unintended behavior of fully resetting an entity's hp or incorrect damage reduction whenever it takes more damage than the max health.

I'm pretty sure this mod combined with Space Exploration's Coronal Mass Ejections has a pretty hefty impact. Game slows to a crawl and Stable Foundation's tick time skyrockets.

might I ask your PC setup ? mainly cpu and whats the difference between this mod ON vs OFF in terms on UPS