@LopataZigota I didn't use this myself (yet) but it might be the one you looking for. https://www.gta5-mods.com/scripts/scene-director

Give it a look and I hope it has the option to start all of their tasks at once.

As an alternative but not good solution though (if you really in need to do this) you can use Simple Trainer. It has an option under Time called Freeze Game. It doesn't exactly freezing but slowing down everything slower than Matrix bullet time and you can start triggering the tasks with Menyoo and they won't move more than a few inches by the time you finish triggering all of them.

If you need to absolutely freeze the game however, you can use https://www.gta5-mods.com/scripts/freecamv-net . Basically go into Freecam mode and press F (I think) to freeze the game. You can't move the camera when you freeze the game but I think trainer menus still can be accessible.