You should avoid the multiplication on each pixel - i.e. "backBuffer[jj * pitch + ii]" is bad.
Also, depending on the pocket pc you use, the backbuffer might be aligned in a way that pitch is much larger than one pixel. So you would have to check the pitch value and if it's larger than one pixel you would have to go in the column direction instead of row-direction.
If you do the right optimizations your performance would increase at least 4-5 times, probably more.