Problem description:
I've been working on a game for sometime now, and for awhile now, my team and I have noticed that 5.12 seems to be incredibly more smooth then 5.13, we've been telling our testers to try the game in 5.12 rather then 5.13 as they too noticed the choppiness present in 5.13
Now with the release of 5.14, not only that it's even more choppy, icons with movement states no longer play when moving.
Here are some comparisons:
5.12: https://streamable.com/rr5gdv
Smoothest movement in comparison to the other two.
5.13: https://streamable.com/btbv3n
Choppy movement, but not as choppy as 5.14
5.14: https://streamable.com/e/fgph6d
Super choppy movement and move state animations don't play.
Workaround for move state not playing: lower mob's step-size, having it the same as the icon-size causes this effect.
The icon being used, to show move state:

With the cool new features, 5.14 bring such as the particle system, it's getting harder and harder to ignore this. Presently, we just tell them to use 5.12 byond when playing, but we now want to utilize 5.14's particle system.
I haven't found any workarounds for the choppy gameplay, perhaps I'm doing something wrong
OR:
atom/animate-movement is stuck at 0? and changing it no longer has any effect on 5.13+