There are articles like https://instagram-engineering.com/dismissing-python-garbage-... which seem to confirm some problems. One of the people involved with this Cinder project was an original author of https://github.com/microsoft/Pyjion (it's now being revamped by a new dev.) Dino had deep .NET/CLR implementation experience and had been the lead for IronPython which I think spawned the interest in perf improvements through Cinder. I hope this effort is more successful for him.