Could be that your save game file is corrupted, sometimes when the saves get corrupted some things can go haywire such as animations, major lag, scripts failing to run, Crashes, or even being unable to load the save. I know you may not want to but if you load back to a save that works fine i suggest using that one from then on even though it may be a bit further back and you lose some progress. Ive had to do it before and it isnt so bad but it does solve your problems. Just a suggestion, hope it helps.
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