My animation is slowed down when far away

Hello,

I have a stupid issue with my NPC. If they walk and are far of me, the walk animation seems to be slowed down. Or maybe it is like if it is not update all the frame.

It render really strange. I think it is an optimization issue and I would like to change the distance at which it happens so it will no be ugly.

Could you help me ?

Thank you for your help and your time
All the best