I already sent a help request in with this same exact info but it is probably worth putting on here as well to see if anyone else has any ideas:

Currently, we are experiencing a number of performance issues with VMix and I would like to get some feedback on what the best way to move forward is.

In a number of our past broadcasts we have had issues with replay not playing back at full speed, videos not playing back(dropping lots of frames, example 1, example 2, example 3, example 4, and many more examples), titles not loading in fast enough(freezes for a while and drops frame), and one recent complete program crash. I have checked the log files for both the recordings and the main VMix logs and they don't seem to provide a clear source of the issues. In the recording logs it almost always says that it dropped many frames "due to source," but this past Thursday while trying to stop the recording the system froze and refused to stop the recording. I had to force stop VMix to get it to unfreeze. Once I did that and checked the log it then said a ton of frames were lost "due to hard disk or cpu" which makes sense in that situation.
Main VMix logs
Recording logs

I feel like we have a powerful enough system to handle what we are doing(Dell 7820, intel xeon silver 4210R with 10 cores, Quadro rtx 4000, 2x 8gb 2666 RDIMM ECC memory, 1tb NVME "class 40" SSD) but clearly we are having lots of issues. Our current broadcast consist of 64 inputs(most being titles and videos/lists), 5 cameras, and 4 camera instant replay(current list of all the inputs we have in VMix and the most recent VMix preset). Half of the time this setup works flawlessly and with no issues and then the other half I have the severe issues I described above(note: when everything is working fine I do not have the issues with the dropped frames in the recording either).

Currently, I am thinking the best way to move forward would be to upgrade the memory to a total of 32gb, add another NVME ssd for replay, and add another SATA ssd for recording storage. Would this be worth the money and do you think it would alleviate the issues?