Timestop is a datapack made for just specifically, stopping time and motion, and experimenting with physics using frozen entities and projectiles. No extra functions, or models. Just the main components. Thanks to this, the datapack is incredibly tiny, a little bit over 100kb, perfect for computers that struggle regarding performance. It is also heavily optimised, using a combination of small functions, arbitrary sorting, and clean code, so don't be afraid to use if you have a slow device.
Extract the latest version of Timestop to the directory C:\Users\[USERNAME]\AppData\Roaming\.minecraft\saves\[WORLDNAME]\datapacks\[Extract the datapack here] (If you're on windows).