Two things I want to quickly point out:
- The repeat loop isn’t necessary, since CharacterAdded:Wait() yields until the signal is called, then returns the character.
- Please do not use while wait do.
That aside, it’s highly unlikely that speed exploiters actually change their frames anymore. All they do is simply change their WalkSpeed and be done with it. The server cannot see the new WalkSpeed the client used, however it can see the client moving faster due to network ownership and thus the replication of that rapid movement.
I’d personally suggest working with the velocity of a character and determine whether or not their velocity exceeds what the server sees their intended velocity should be.