I would always do client because of performance but the problem is that with my nuke if someone joins later in the game, the nuke is only tweened via fireallclients so only the clients who were already in the game at the beginning will see the nuke. Other players who join later wont.
With the server, everything is synced so players who join later will see what’s happening.
I have 4 tweens which move the instances. The instances are quite large.
It may impact performance but I would suggest just making said tweens run through a remote event via the server-side and work on optimizing the code and assets(reducing particles, parts, etc.) if you wan’t to have everything fully synced for all the players in the server.