I'm looking for a graphics card that minimizes the amount of time taken to upload 4k video frames from Opencv to the GPU. OpenCV uses opencl behind the scenes to do GPU related calculations but I've found that the upload/download time to the GPU is the biggest bottleneck. How do I go about evaluating GPUs and what specs should I be looking at on the graphics card to see if it has the attributes I'm looking for (uploading to graphics card quickly with 4k frames)?

I'm looking for a graphics card that minimizes the amount of time taken to upload 4k video frames from Opencv to the GPU. OpenCV uses opencl behind the scenes to do GPU related calculations but I've found that the upload/download time to the GPU is the biggest bottleneck. How do I go about evaluating GPUs and what specs should I be looking at on the graphics card to see if it has the attributes I'm looking for (uploading to graphics card quickly with 4k frames)?

Edit:

Ideally I'd like the machine to cost <= 500 dollars in total, including the GPU (I am open to building a completely new machine for this).

Edit 2:

In short, the gist is to build something optimized as much as possible for OpenCV (with OpenCL) and video processing high res (4k) in general