In my game there are explosions, and in order to make it seem intense I added a screen shake, however, the screen shake can only occur if they are within a certain range (roughly 50 studs or so).
Is it quicker and less strenuous to either:
For the server to cycle through all the players and check their magnitude assuming the character exists, note that the server is already doing some heavy stuff.
OR
To use the FireAllClients() event so that the client can work out the magnitude in a LocalScript.

3 comments
First solution. Then fire clients to shake the screen. Prevents potential exploits. Don't worry about server doing heavy work, magnitude checks are very fast. If you are concerned, you can always keep an eye on script performance window. Anything less than 3% is ok.
I don't really mind the screen shake on the client side, as it's only a screen shake. Unless in terms of performance, it is better to go for the first one?
lol