So basically this will allow for entity lag to be decreased, whenever an entity spawn, this will bundle them into one with a tag. This will cause the server to only need to calculate the physics and maths for 1 entity while still keeping all of the mobs. This would greatly improve lag created by entities.
https://www.spigotmc.org/resources/crop-hopper.48715/--> only for cactus farms and works a bit different than the other one.
https://www.spigotmc.org/resources/hlr-crop-hoppers.34051/-->HLR is a simple yet powerful plugin aimed to reduce entity lag by tweaking how hoppers work. Though, it only tweaks specific hoppers as not to completely change the vanilla experience. This plugin is especially helpful if your server has a lot of gigantic farms (including mob farms), such as typical skyblock or factions servers.
--> Vanilla hoppers will still exist and won't affect anything already build
There are many version of it, and not sure which one is the best one or the most configurable.