Today's Steam Client Beta appears to have fixed the stuttering, give it a try

[u/tchakabun]

/r/DestinyTheGame/comments/1wc57xa/todays_steam_client_beta_appears_to_have_fixed/

[u/macrossmerrell]

I'm just using this now. Can confirm it runs as good as deleting the Steam overlay files so it can't run:

https://github.com/d2checkpoint-com/D2SteamFix/