How can I specify (speed up) the rate of a ROS Subscriber in MATLAB?

I create a subscriber for the /camera/rgb/image_color topic to get camera input, but the subscriber only updates what seems like once a second. How can I speed this up? After hours of testing I'm positive it's not network latency or any sort of hardware issue but it's with the way MATLAB creates a subscriber using the rossubscriber function. Can I get around this somehow?