Confirming. Experiencing this for a few weeks now around the area of Legion square all the way up to the Davis clothing store.
No background processes running, reinstalled the game to my SSD and even adjusted the graphics to lower settings. Single Player, GTA Online and other servers run smooth. To me it seems like a server issue since everything else runs fine.
Somewhat extreme example, but this is how I experience it: https://streamable.com/ymlhqp
Did you both find a solution? @xiAshes @Jennie
Edit: just read your solution @xiAshes