There should not be lag in VMSA. I am in a small zone with at most 10 enemies on screen. I've seen videos of PC players playing it in 60 FPS. I'd take 30 FPS at this point.
I can teleport to smaller zones like Betnikh and cast 4 consecutive spells and it feels smooth. I feel like a god when it plays like that. Is there something about the amount of players attempting VMSA that effects my framerate? I've completed it on normal once and I can't remember it being as full of lag as veteran is. Before I get the same copy and paste reply about clearing cache and rebooting my Xbox, know that I already do this once a day and no it doesn't help.
When Cyrodiil lags, I understand that. When VMSA lags I'm done with it.