Weird behaviour of objects and mobs

Hey there, 

It's been already a while, since I've last played Minecraft. I'm sorry to report some bugs I've been noticing for a couple of months already. I've tried to solve them, leaving unplayed the game for a while, but every time I got back, those bugs were always there. 

It seems the game has been partially slowed down. For example, when I want to use a bow, the arrow, that's being shot, doesn't get further powerfully anymore. That usually happens when I want to kill mobs from long distances with a bow.  Moreover, villagers and other mobs, while they walk around, act weirdly. I'll try next time to make a vid for you, as you can see with your own eyes, what I'm talking about. 

I don't know whether other players have already reported something like that before, but I would like to know if somebody was in the same situation as mine. 

I would be so glad if you could help me, solving this weird bug. 

Thank you in advance!