I've recently encountered funny problem with Skyrim engine. When you try to climb a horse that stands right on locations delimiter you start to fly in a very funny way though the whole map. It seems to be an engine bug, hope that developers read this forum and it will fix this minor issue one day.
My installed version is a Legendary Edition 1.9.32.0.8. There is a save for easy reproducing but I can't find attachments on this forum and can't post links here, gg.

Do you have V-Sync on?

This can also happen if your system puts out more than 60FPS (has to do with how cells render) and if this is the case, then it can cause other problems too.

Most people clamp their frame rates in this game as it does a lot of good things for you besides stopping this, like reducing micro stutter. There are some third party tools that can clamp this, but I like to use the anti stutter mod. There are some newer things out there that also do this but this works for me

http://www.nexusmods.com/skyrim/mods/2581/?

Note, you can change the frequency clamp once the game is run and the ini file for the mod is created. Best range is somewhere between 40 and 53. Over 54 and other minor issues start to occur.