I don't know if I am a pro, but I am 35+. I almost never track the deck, though I sometimes do it when the deck is still small or new, because it is easy enough. I usually don't track anything, but would try to reconstruct things in my head to see the Curse or Ruins split or the score when playing without VP counter (which I hate).
I would say concentration is way more important than tracking. And multitasking takes away your concentration. I know because I do multitask when playing (other than tournament games -do not confuse with Tournament games-) and I notice it seriously affects my play. If I play concentrated and slowly, I play much better, even if I track nothing.
Of course, tracking helps, but I would try to concentrate more, I think it affects your game a lot more and, well, it is impossible to track anything without concentration anyway.
In my experience, when I concentrate, I maintain a 40 something level. When I do not, I fall to 35 or so. I usually choose not to, because I enjoy it more when I am not tense trying to win. Tournaments provide enough full-concentration games for me. Also, people you play against is also not taking it seriously many times, so ranking is not really the best measure on how good you are. Tournaments are. So, if you really want to get better and keep track of it, my advice is, join Dominion League or some other when there are others and use that to test your current skill, not the rankings.