Hi! 
I can't use English well..but I have some question about Blt and Flip. 
I used to heard " If you use Blt to copy(blt) the backbuffer to primarysurface that will faster than Flip!??". Are you understand? Is this true? 
Thank.

Nope. 

Flip is faster. Blt requires you to copy the entire surface from the back buffer to the primary surface. This is usually a few hundred kilobytes. 

Flip basically swaps pointers. An exchange of 8 bytes takes place, and it's heaps faster then a blt. That's how the theory goes anyway.

Thank you