We use JXS when latency is critical. Most h24/265 decodes will have a 10 frame glass-glass delay, JXS drops that to 3 or 4, at a cost of bandwidth (our UHD jxs streams are 1.5gbit rather than 200mbit for hevc)
But for some reason you can't make use of that and have to burn bandwidth instead.
https://www.obe.tv/how-to-lie-about-latency/
Bandwidth is cheap -- basically free, especially at this bitrate.
It's not that you should have gotten a magical 10ms latency glass to glass, it's that you should have been able to get 4 frames latency on h.264. But something prevented that, so I'm sad about it.
(And if you say the bandwidth was fine in your situation I won't argue, but using more than a gigabit extra is not usually thought of as free.)
A lot of our customers are moving their grading systems into data centres and streaming the images over IP back to their grading suites.
I've got it down to less than 1 frame for encode-transport-decode, but you've still got to copy the image to an SDI card and wait for that to clock out.