A replay buffer feature that
1) Allows the user to configure the time for(say 15mins)
2) Allows the user to set a hotkey to save that buffer to disk
3) Allows the user to scale the output size up or down(say all sources are 4k, but the replays need to be 1080)
4) Does not eat up more than 1-2GB of RAM for 1080p60 footage

Background:
Open Broadcaster Software/OBS-Studio has a replay buffer output option that allows me to say "store the last 300 seconds of footage continuously in RAM and when I hit <keystroke> save the last 300 seconds to an AVI file on disk." I would like this feature in vMix because the video delay and the instant replay eat up 100+GB for 200 seconds of 1080p60 footage whereas OBS-Studio has 300 seconds of 1080p60 footage in RAM using 900MB. The problem is streaming AND external output eat up serious amounts of CPU resources to the point of maxing it out.

+1