SUPER LAGGY FOR NO REASON

I'm SUPER laggy on gta v, even more laggy in Online mode. and i checked in my task maneger and my CPU is at 1% before i launch the game

PC Specs:

i5 4460 3.2GHz

GTX 750Ti 2GB VRAM

4GB RAM 1600MHz

and im on the lowest settings. no advenced settings on. on 1080p. averege FPS: 25 (on Online: 19)

and i always drop to 5. help please?

same tho

same tho