When I have lots of animation for an object and want to re-arrange the animation list(by clicking it and drag it up or down) it become so slow and laggy, hopefully the performance got improved / completely change the way to manage animation list. When the animations is just a few there is no problem tho.
This may be dependent on your PC, I have a player object with approximately 50 animations, with at least 4 frames each, and can reorder the animations without any slowdown.
If you list out your PC specs (GPU, CPU, Ram, Operating System) one of the devs may be able to give more details if it’s a minimum spec requirement issue, or something that could be improve optimization wise.