Seriously- you need to turn both of them off-


it doesnt affect overall performance
its causes glitchiness on playback-


you dont want anything reading the discs at all while you are playing back movies

file sharing has constant background disc activity - which does affect playback

and screen sharing captures the entire screens and transmits it over the network.
And quite honestly this is a really bad idea when you are trying to maximise graphics performance

you really really dont want either of these activities going on in shows - ever

Even spotlight needs to be turned off- you dont want the discs being indexed either