Any suggestion about UI design books?

[twicave]

Several days ago. I made a experiment about UI refresh rate.
I found if you draw widget every time, the refresh speed will be very slowly.
but if you stored widget content into a QPixmap, the refresh speed can improve about 10 times.

Experiences like that should have been written into books.
But where are they? can you give me some suggestion? like books, articles, lectures...