Will excessive commenting of code slow execution? [duplicate]

Question

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Closed 9 years ago.

Possible Duplicate:
Do comments slow down an interpreted language?

Will there be noticeable performance degradation in the execution of a large .py file if more than 75% of the lines of code are properly commented?

Answer 1

No

When you run python, the first step is to convert to bytecode, which is what those .pyc files are. Comments are removed from these, so it won't matter^*.

If you run with the -O or -OO option, python will produce "optimized" pyo files, which are negligibly faster, if faster at all. The main difference is that:

• with -O assertion are removed,
• with the -OO option, the __doc__ strings are stripped out. Given that those are sometimes needed, running with -OO isn't recommended.

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^* it's been pointed out below that .pyc files are only saved for modules. Thus the top-level executable must be recompiled every time it's run. This step could slow down a massive python executable. In practice, most of the code should reside in modules, making this a non-issue.