Don't know if this is applicable, but when I use the older menu - which gives the option of quick load vs load - I find that you'll be able to control the speed (assuming you click quick load) AFTER letting your replay play out in its entirety once without resetting (r). The speed multiplier starts off grey and turns black after one run of the replay.

The regular load button takes a brief moment to play the replay (but you should be able to control the speed right as it loads up).