I agree. I always considered maintainability to be the main part of technical debt. You do it quickly, but only you understand how it works. Then you refactor i

I agree. I always considered maintainability to be the main part of technical debt. You do it quickly, but only you understand how it works. Then you refactor it (preferably against [unit] tests). Nobody wants unmaintainable code in their codebase yet it sometimes appears... The only aspect of performance I would consider technical debt is how your software scales. When you have 2x as many users will the load be 2+epsilon times higher or 10 times. Or what if 10% of your users performed some action at the same time.