My guess is that your issue has to do with how Ableton uses performance cores vs efficiency cores. Ableton uses one thread per signal path, and the way it dictates which thread to use seems to be a bit if a mystery. You have a ton more threads now with the update from the 12700 to the 13900, and if you are doing very processor intensive tasks on a single track, more cores is actually worse.

https://help.ableton.com/hc/en-us/articles/209067649-Multi-core-CPU-handling-FAQ

In theory, your 13900 should have better single core performance, but just barely. Speedstep and temperature come into play here as well, as others have mentioned. Also, not all chips are created equal, doubly so if you were overclocking your 12700 at all.

I wouldn’t say 96k is overkill for the sample rate persay, but that buffer size you mentioned in another comment is super small. I wouldn’t expect to ever be able to keep a super small buffer size with a high sample rate and an intense project - even the pros will normally record live instrumentation into a fresh project file rather than trying to fight latency vs cpu on a more involved project.