Disabling the GIL can unlock true multi-core parallelism for multi-threaded programs, but this requires code to be restructured for safe concurrency, which isn't that difficult it seems:
> When we found out about the “nogil” fork of Python it took a single person less than half a working day to adjust the codebase to use this fork and the results were astonishing. Now we can focus on data acquisition system development rather than fine-tuning data exchange algorithms.