I'm not a big fan of baking because it loses many of the best parts of the physics. Movement is no longer dynamic. Baking usually requires many keys and the tools needed to reduce the number of keys or manipulate many keys are complex. I've posted about baking previously, eg:
https://esotericsoftware.com/forum/d/25169-baking-physics-and-looping/2
In 4.2.32-beta (released minutes ago) we've added a Warm up
slider for image and video export:
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It works as I described in my second post in the thread I just linked.
I made an animation with physics that loops perfectly, but starts in the middle of a fast motion, then exported a GIF with 0 warm up:
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When the physics start out stationary, the GIF doesn't loop smoothly.
Here is the exact same animation with 1 warm up iteration:
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By playing the animation once behind the scenes before the export, the physics are in motion when the export begins and it loops much better.
Warm up can help in many situations, but some use of physics can never be looped.