Turn off the GPU acceleration.
Thanks a lot.
It really helps!
Now I'm using Core-i7 processor with built-in videocard.
Should external videocard help with processing performance?
The GPU feature in LR is not really ready for Prime Time. I have a GPU that can use it and LR runs faster with that feature turned off.
So it is Hit and Miss whether adding a discrete graphics card will help. Some have said they have a GPU that helps but from what I read, and my own experience, most of the time LR runs better with it turned off.