Strange lag (Grand Theft Auto 5)

Guys, Hello!
The situation is this, recently purchased the Asus TUF GAMING FX505 DY. Like , all right, fine. Download pirates GTA5 and has recently started to lag. First, I have to say, I'm no expert and not very good at all, but I will try.
In the game, the graphics settings internal memory is 2993 and was 4090. The filling is in the middle of the scale and burns with green color, but still slow.
The feature will make a screenshot.
What can be thoughts and ideas, please help!