Nate a écritThis is fixed in 3.5.08-beta. We also did a number of optimizations to be more efficient with a large number of bones and slots. However, it is somewhat abnormal to have 1400+ bones and 1400+ slots in a single skeleton, so Spine has not been optimized for that and you may see slowness in other areas. It should work well up to 1000 bones, though you may need to turn off auto keying.
Thank you, it's already very helpful.