I would suggest to add a permission to change the max speed a user is allowed to set by himself.

Because i want to give /speed to player on a creative world, but if they are flying around with speed 10 it causes lags. Speed 5 is quite okay.

If you could add this it would be awesome.

Isn't there already a config setting for this?

Ohhh...

Now i understood how it works O.o
Sorry, can be closed :P