I'm only posting here to add my 2 cents in the hope that the more people that complain about this more likely it is that Adobe will fix this problem. It seems very common an quite basic at it's core. FIX THIS ADOBE! We are paying for this product.
I am having the same problem as everyone, more or less. I have only recently noticed that my stabilised footage is often the clip that causes it, but it does happen elsewhere.
I have found SG to be very sliggish even when I have not encountered the the GPU resources warning message. I have to jump forwards a frame with the arrow key before I see change in the clip, with each adjustment! And moving the sliders etc is also sticky.
I have a pretty powerful machine and am only running a 1080p monitor. This should not be happening.
4.3GHz Core i7
16Gb 1688 MHz Ram
NVIDIA GeForce GTX760 2048Mb
250Gb SSD for system drive
I went for less RAM and a graphics card, but I still think this system should be able to handle this. Tell me if I'm wrong.