Browsing Louisiana French translation

11.

Usually the problem is isolated to small sections of code. Pick the worst place and concentrate on that first. Once that is done, rerun the profiler and repeat. As you proceed the gains made at each step will get less and less, at some point you will have to decide that the results are good enough. If your efforts are only extracting 10% improvements then you are well past the point where you should have stopped.

12.

Don't forget the big picture. For example, rather than just trying to speed up a piece of code, ask yourself if it needs to be run at all. Could it be combined with another piece of code? Can the results of previous calculations be saved and reused? It won't even need to be optimized if it is in a place where the user is never going to notice it. Worse still, the code may already be optimized and is doing the heavy calculations now to avoid doing them later. Code does not run in isolation and neither does the optimization process.

13.

Hints

14.

The Fundamentals

15.

Re-run your benchmark after every change you make to the code and keep a log of everything you change and how it affects the benchmark. This lets you undo mistakes and also helps you not to repeat mistakes.

16.

Make sure your code is correct and bug-free before optimizing it. Check that it remains correct and bug-free after optimization.

17.

Optimize at the high level before optimizing the details.

18.

Use the right algorithm. The classic text-book example is using quick-sort instead of bubble-sort. There are many others, some save memory, some save CPU. Also, see what shortcuts you can make: you can do quicker than quick-sort if you are prepared to make some compromises.

19.

Optimization is a trade-off. Caching results speeds up calculations, but increases memory use. Saving data to disk saves memory, but costs time when it is loaded back from disk.

20.

Make sure you choose a wide variety of inputs to optimize against. If you don't it is easy to end up with a piece of code carefully optimized for one file and no others.