Minecraft's movement system is inefficient and slow, especially when you have entities moving far distances in a single tick, this reduces the time it takes to compute movement significantly.
Every tick, when a entity moves, Minecraft collects every block inside the volume the entity sweeps through, then resolves against every single one of them.
But this mod resolves collisions along each axis of motion independantly, so it only checks against the blocks in its path making it much faster and still matching vanilla exactly. It also caches the movement each tick so if multiple entities are sharing the same path it can skip recalculating the movement making machines like Cubicmetre's Orbital Strike Cannon significantly cheeper to run on your world/server.
You may use this mod in your modpacks.