OK, yea, it makes sense that you can't replace the GPU, perhaps mostly because it is a mobile GPU, whereas the CPU is a desktop-class i5 (or i7).
Now that I've had a few hours with my i5-4690 (3.5GHz/3.9 Turbo) and the R9 M290x, and I can report that yes, Mission Control does take an extra second or two, which is disappointing, because I use it all the time. I doubt, however, that the M295x would make any difference in this regard.
I think it might be a software issue of a brand new OS and its equally as fresh hardware counterpart.
Now that I've had a few hours with my i5-4690 (3.5GHz/3.9 Turbo) and the R9 M290x, and I can report that yes, Mission Control does take an extra second or two, which is disappointing, because I use it all the time. I doubt, however, that the M295x would make any difference in this regard.
I think it might be a software issue of a brand new OS and its equally as fresh hardware counterpart.