How to speed up camera resolution change in OpenCV?

Question

OpenCV

Hello!
I'm capturing video from the camera (At the moment it's just the output of imshow()), in the process I'm trying to change the resolution with:

_cap->set(CAP_PROP_FRAME_WIDTH, possibleRes.width);
_cap->set(CAP_PROP_FRAME_HEIGHT, possibleRes.height);

But each such change takes 2-3 seconds (even when changing the resolution to 640x480) Is there

any way to speed up this process?
The camera is a regular webcam, via DirectShow (no native drivers are provided with it).

PS I understand that with a high resolution, due to insufficient USB bandwidth, there will be low FPS, but here it's just a big delay when changing.