You're doing an activity which is potentially beneficial (your tools become slicker), yet are approaching it in a compulsive manner to the extent that it is no longer beneficial (you're wasting your time on it).
I'd be surprised if anyone on this forum doesn't suffer from that problem under one guise or another. It's an obsessive-compulsive behaviour which you justify because it does bring some benefit, and that's what makes it hard to crack.
I suggest the first thing you do is get clear about how much tweaking is beneficial, and how much of it is compulsive. I agree this is tricky, it's arbitrary, and you've got a compulsive craving there to warp your perception. Still, set a point, perhaps a time limit as suggested by @asfallows.
Now that you can identify what counts as compulsive and counter-productive behaviour, which in this case is following your craving for perfection/optimisation, you need to practice not indulging in it. The way to beat your craving for something is to be comfortable not having it. Practice denying yourself what your crave, and feeling amazing about yourself for having the strength to do it.
So, choose to deliberately work with a less than optimal system. Notice how uncomfortable you are with that, and choose to endure that discomfort without giving into the urge to tweak. Make that "accepting imperfection and not giving into tweaking" your target behaviour.
You can help yourself by keeping a score-sheet: every time you successfully overcome the temptation to tweak, draw a little smiley face or so, and count them after a while. You'll soon see how good it feels knowing that you have control over your behaviour and are succeeding at doing something difficult (to you, difficulty is always relative).
Of course, you might want to look into why you're avoiding your tasks too :-)