Is the speedo paddle wheel on one side or the other? if so, this has been a reason for one tack being faster per say than the other. At least on "MY" boat it is! The paddle wheel is about 8" ff center to port, so many times since the wheel is deep and flat when on starboard tack, we are faster than on the port tack where the wheel will be pointing sideways for lack of better term or way to say it!
I list to port also a bit.
My rig is pretty well centered, as I had a crew up to the top, measured side to side a the top, upper then lower spreaders etc. tension is equal on both sides........
She drives me boat,
I drives me dinghy!