Lags on laptop (Assassin's Creed 3)

Good afternoon! Two years ago I played asassin 3 on a laptop with Windows 7 home, the game was acceptable, I passed it and forgot. Somewhere a year later, I changed the disk on my laptop and changed the Windows to Windows 7 professional (disks, what's new, what's old: ssd and one firm) and decided to re-run the assassin, but he began to lag furiously. And here's the question why this could happen: Bad torrent? (took from a hatub) How did it affect the disk? Change of system? New version of asasin after remastered to lag? Virus? If anything is pretty old, asus k540s if I'm not mistaken.