It is still possible on PC

1. Join a public session
2. Go to in game settings and use "Windowed borderless" instead of fullscreen & apply them.
3. Ctrl + alt + delete - It'll open task manager with GTA running in the background.
4. Click on performance, click on open resource monitor, click on CPU, find gta5.exe from the list it'll be in black letters.
5. Right click on gta5.exe, suspend process. The game will freeze at the background.
6. Wait for 10 seconds.
7. Find gta5.exe from the same list, it'll be on top, in blue letters this time.
8. Right click on gta5.exe, resume process.
9. Close all task manager tabs
10. Watch the whole lobby leave, grind in peace.

Should take you a minute.