How costly is changing a static mesh?

When using pooled actors that can have a variety of looks but the same functionality, is it better to:

A) Have a pool per static mesh
B) Have a common pool and set the static mesh on spawn
C) Have all static meshes on every actor and control the visibility

The use cases can be projectiles, enemy swarms, VFX. The meshes are not animated, only moved. Spawning from pools is frequent and mesh changes very likely.