For hardware usage reference.[1] You didn't state how much RAM you have. For all I knew you could be running a potato with 8 GB. It happens more often than you think. Don't assume people know your system specs. My rig is much weaker than yours though, and did do a run for 90 minutes with only 16 gb, so it might not be a RAM issue.
[2] Your virus scanner might not like Delta Zone and could be running concurrently. Avast Antivirus hated 7 Days to Die, and caused a similar situation, where I had plenty of RAM for 7DTD, but the AV was eating up a further 7 GB of RAM, causing a RAM depletion event.
[3] When troubleshooting issues, knowing if there is a resource depletion, is an important step in coming up with a solution. That is why I suggested Task Manager first.
[4] Don't get snippy with the help, unless you are okay with getting none after a while.
On High, High, 1080p graphics and res. I saw 5.4GB vram usage, 13GB system Ram usage. Didn't seem to climb over time as in memory leak, but then I didn't move around much.
Just played around a bit with the tentacles lol. Combat/loot and pretty much everything way too janky for me.