Picturebox -working with high resolution image

Question

Hey guys, I'm stuck with this: I've got two forms - 1.: There's a trackBar 2.: there's a pictureBox, size is like 1024/768, whatever (small). Size of the image in the picturebox is like 20000px * 2000px (really big). While scrolling the trackbar, the image is moving to the left or to the right (viewing this large image in small picturebox, like if I'am looking into the camera). The problem is -> this operation has to be smooth, no lags at all. Rectangles, threads (many), delegates, doublebuffering, nothing works. The problem seems to be that CPU has to do everything an its loaded on 100% while scrolling the image (load large image, make rectange with the viewed area, show the ractangle in the picturebox). Anyone knows how to make this scrolling smooth? Any advice appreciated! Regards from CZ, Andrew M.