blender running so slow i can take a nap when clicking a menu I have a big problem. It's been happening for a long time and it's really urgent as this is payed work. 

For some reason my project is running so slow I can't even click on the menus. I literally went to bed yesterday after clicking a menu just so it could load in the option to delete it. 

I am like 4 days over the deadline and I need urgent help (tell me if you want the packed file, I'm uploading the normal one now, please tell me if you have the same problem as it might be my pc).

Oh  and yes i am working with really big particle systems but even with those completely deleted i get this performance. (for some reason the problems usually start after I have put in something really demanding so it might be that the demanding tasks are still doing the pc from behind even after I've deleted them)

thank you btw for any answers
Sounds like a memory shortage. Add more physical memory to your machine, reduce the complexity of your meshes and particle systems (when allowed) or pay for an outside cloud rendering service.

In any case, it may be more cost effective to just hard-reboot the machine instead of waiting for the File -> Quit menu to show.  I hate hard crashing my machine, but I'd likely get things rebooted, modified however needed, and running at normal render speed sooner than by shutting down properly.

But first, just in case - check if you're running some other apps at the same time that might be hoarding memory.  Email, web browsers loaded with pages with bad javascript, movie players, another instance of Blender.