Would like some advice on wether BGIII will run with any acceptable speed. I only saw minimum OS requirements on The store page.

My first choice would be to be able to play it on my Macbook PRO (late 2015). And as an alternative I have a PC laptop which can just about handle games like Mutant year zero but not Fallout 4...

So anyone with enough experience of the game that can give me a hint?

Only hint I could give you would be the spec on my old PC which I'm using to test the game... Intel 4950 cpu, 16 gig DDR 3 and a 1070 TI, Windows 10 using Vulcan... game has been stable, left it running and went out , and was still playable when I got back 9 hours later. This system runs FO 4 fairly easily with mods.