The thing is that untangling the logic often reveals either new feature opportunities that would have been ugly to implement previously, or new optimization opportunities because the code is clearer, and possibly two things that seemed unrelated before are now obviously related.

If I can't figure out how to make code faster without cheesing it I'll just follow the campsite rule and hope for inspiration (the more you work with code the more you understand it, and I might as well clean while I'm here)