Seeing the same behavior on my install, with memory climbing within a minute or two to 100% then the machine starts to swap and grind to a slug in performance. Have been running the same hardware config for a year or two with no issues, had to reinstall/rebuild earlier this week with clean install of Windows 10 Pro on same hardware. Running 12 cameras, always ran about 4-5GB before, now consuming all 8GB on machine.
My install ran fine since 5/26 after rebuild until last 24 hours where this started. I see two windows updates added KB 3173427 and KB4019474 added in past 2 days. Rolling those back to test now. Same issue repeated when I rolled back BI to 4.5.1.x and 4.5.5.x