Jython was released 22 years ago
IronPython was released 17 years ago
To date, no Python implementation has managed to hit all three:
1. Stay compatible with any recent, modern CPython version
2. Maintain performance for general-purpose usage (it's fast enough without a warmup, and doesn't need to be heavily parallelized to see a performance benefit)
3. Stayed alive
Which, frankly, is kind of a shame. But the truth of the matter is that it was a high bar to hit in the first place, and even PyPy (which arguably had the biggest advantages: interest, mindshare, compatibility, meaningful wins) managed to barely crack a fraction of a percent of Python market share.
If you bet on other implementations being the source of performance wins, you're betting on something which essentially doesn't exist at this point.