If you assume two completely separate implementations where there is an #ifdef every 10 lines and atomics and locking only occur with --disable-gil, there is no slowdown for the --enable-gil build.
I don't think that is entirely the case though!
If the --enable-gil build becomes the default in the future, then peer pressure and packaging discipline will force everyone to use it. Then you have the OBVIOUS slowdown of atomics and of locking the reference counting and in other places.
The advertised figures were around 20%, which would be offset by minor speedups in other areas. But if you compare against Python 3.8, for instance, the slowdowns are still there (i.e., not offset by anything). Further down on the second page of this discussion numbers of 30-40% have been measured by the submitter of this blog post.
Actual benchmarks of Python tend to be suppressed or downvoted, so they are not on the first page. The Java HotSpot VM had a similar policy that forbid benchmarks.
If you assume two completely separate implementations where there is an #ifdef every 10 lines and atomics and locking only occur with --disable-gil, there is no slowdown for the --enable-gil build.
I don't think that is entirely the case though!
If the --enable-gil build becomes the default in the future, then peer pressure and packaging discipline will force everyone to use it. Then you have the OBVIOUS slowdown of atomics and of locking the reference counting and in other places.
The advertised figures were around 20%, which would be offset by minor speedups in other areas. But if you compare against Python 3.8, for instance, the slowdowns are still there (i.e., not offset by anything). Further down on the second page of this discussion numbers of 30-40% have been measured by the submitter of this blog post.
Actual benchmarks of Python tend to be suppressed or downvoted, so they are not on the first page. The Java HotSpot VM had a similar policy that forbid benchmarks.