You're possibly misunderstanding how 1:1 previews work, especially in relation to how long they last.
Put simply, when you edit a photo the existing library preview is replaced with a new preview, which initially is only of large thumbnail size. When you next bring the image into the Library module in the Loupe, a new standard-size preview is automatically built. Thus if you started with a 1:1 preview, then edited the image, the best you would end up with is a standard preview.
1:1 previews are great for reviewing images, especially for focus checking, in the Library module....and that the 1:1 preview will remain until you start to edit the picture, after which it's gone.
The GPU feature in its current implementation offers benefit only in certain Develop functions. It does not, therefore, yet provide any assistance in 1:1 preview rendering, so it's no surprise that the 1:1 preview rendering time is pretty similar to LR5. That's what my own testing reveals as well.
and sometimes they NEVER finish loading
and then the last thing done was render 1:1 previews,
and then you come back to look the next day, no changes applied,
you have to do it all over again
So i just built a bunch of 1:1's, go out for a while, come back
and start viewing and 25% of them I get "loading". Not as long
as a regular preview, but still, many seconds per picture.
That sounds like a different problem, because that really shouldn't happen. It's odd, though, that it's only a portion of them doing that, so are you certain that you'd selected all the photos that you'd built the 1:1s for? Assuming you had, then I'm stumped as to why most are OK, but some are not.