A normal spawn actor, engine default, will take some impact on fps.
If you leave the reconstruct option turned off, that impact using the OBJ Pool is reduced by 70%~90%;
With that reconstruct option turned on, the OBJ Pool will reduce spawn impact by 40%~80%, so if you spawn a projectile every frame that would give your spawn function only 40% performance boost instead of ~90%.
If the projectile isn’t spawned every frame, that’s fine.
On construction script you can set the initial (exposed) velocity of the projectile, maybe that’s why yours don’t move, no speed set on spawn.
Also make sure you use the custom projectile component provided; the default projectile movement component will not work on object pools.