Help with poor playback scrubbing - hardwired AppleTV's

With the Olympics here, our DVR has been stressed a bit more than usual with a continuous 1-2 recordings throughout the day/evening, and I'm seeing really poor performance during playback, especially fast forwarding and scrubbing through recordings. Delays in FF/scrub are on the order of 5 seconds, and sometimes stops playing smoothly. I've been running the DVR for a few years and never seen such poor performance and can't figure out what to chalk it up to... 2 simultaneous recordings and 1 device playing back I wouldn't think should stress my server or hard drive, but I'm at a loss.

Setup is an M2 Mac mini, hardwired through Ubiquiti network equipment. We have 3 latest gen 4K appleTVs throughout the house, all hardwired as well. Storage is a thunderbolt raid enclosure, with 4x14TB drives in a SoftRaid 1+0 config.

My partition for the Channels data is HFS+ journaled, and speed tests between 200-400 MB/sec R/W depending on the load. (The other partitions of the Raid array are used for Time Machine backups). I initially wanted to blame the hard drive for poor performance, but I can't see how with R/W speeds like that.

Speed tests from the AppleTV's to the internet can max out the connection, 940Mbps download, and the playback issues are across all the AppleTVs, so I can't blame a particular network cable.

Logs don't show any signs of playback issues, and live video doesn't have any stuttering, only recorded content.

Any suggestions on what else to try, or things to look at? Thanks in advance.

Can you run the resource intensive troubleshooting tests during one of those instances where you’re having the bad performance and see if that sheds any light on anything?

Just tried to simulate since I'm away at work, but two recordings plus a remote playback. All green, Disk IO is interesting to watch as it starts at ~500MB/sec and backs down to ~295MB/sec Write, but Reads > 10GB/sec... maybe too small a read sample to be accurate?

Take a look at the smart data for your hard drives.

All 4 drives say: Verified

Anything in the system error log?

Can you defragment the array?

Nothing in the DVR log.. how does one defragment these days. Is that even possible on a Mac?

How about the system log? Someone else needs to help you with mac os