500 lines a day feels about right taking the whole project into consideration. I ported a physics engine from C to Javascript a decade or so ago. Once I was in

500 lines a day feels about right taking the whole project into consideration. I ported a physics engine from C to Javascript a decade or so ago. Once I was in the swing of it, I did a lot more than 500 lines a day too. But I also spent a few days reading the original code. And I tweaked how I wanted to represent everything in javascript - which slowed me down. I should have just ported it directly, then refactored afterwards. And I spent a few days at the end tracking down some bugs that snuck in. In retrospect, typescript would have been a better choice. But I hadn't learned it yet. The best days I ported maybe 1500 lines. On the "worst" days I did 0 lines. In all, 500 lines a day feels like the right ballpark for this sort of work.