Slow video on Mac with Intensity Shuttle

For the last few months I have not been able to get high quality video on the Mac when using anything except the built-in webcam. The 20 fps video that I've been feeding via Blackmagic Intensity Shuttle looks perfectly fine on the Mac that's hosting the feed, but the participants are all seeing about 10 fps, if that. Connect support told me to use the browser as there's a known bug in the add-in, and that did improve the quality since the add-in was only giving me 1 fps. Is anyone else having this problem or anything similar?