This is anecdotal evidence but I'm a trans woman who transitioned at 30. I ran cross country and track and was the fastest kid at my school in a relatively competitive program. I got depressed after college and gained a bunch of weight and only ran sporadically. I started HRT, I keep my T levels in the lowest range that's healthy for cis women. I got the urge to start exercising again. I now run more than twice as much as before, lost 40 pounds, and do roller derby on top of that. I'm still not as fast as I was when I was mostly sedentary, drinking beers every night in my apartment. I don't know if I'm faster or slower than I would have been if I was a cis woman but I did take a pretty big hit.