I can usually manage to send about 6-10 sets of images to PS for compositing, one after the other, before the spinning beach ball stops me and I must go make a coffee. The ideal scenario is that I would be able to select all the pairs/groups that need to be composited and place them in a batch list and they would all process in the background while I worked on other shots.
But, I understand that LR and PS need the CPU and the GPU to process the conversion from RAW to TIF. That's fine. But now I'm back to sending one pair or group of shots to PS as layers, waiting for about 10 seconds for the dialogue box so I can tell it, once more, to continue anyway, before I select the next shots and send them as layers.
I guess I am drinking less coffee...
The GPU only speeds up some develop processes IF you are using a 4/5K monitor. With smaller monitors it may even slow things down. So turn it off and see if you can see the difference. IMO it ought to be off by default. Most people won't benefit, and as many have found, it can cause more problems than it is worth, depending on your graphics driver.
The point I was making is that I do understand the computer needs some time to process from RAW to TIF but that, no matter how long that may take, a batching queue would be more efficient than having to wait and click on "Continue Anyway" in a dialogue box for each one.