Illustrator freezing every ~4 seconds for ~0.5 seconds - continuous, rhythmic stutter making work difficult!

I’ve been using Illustrator for well over-20 years and have never seen this issue at this intensity. Illustrator is freezing every 4–5 seconds, like clockwork, for about half a second. It’s rhythmic and continuous, and it’s now becoming difficult to work with.
No other Adobe apps do this. No other program on my system does this. It is 100% Illustrator‑specific.
I spent my entire Saturday trying to isolate the cause. Here’s what I’ve already done:
•     Reset all Illustrator preferences
•     Renamed/deleted Adobe cache folders (AppData → Roaming & Local)
•     Checked mouse settings, polling rate, drivers
•     Checked Windows registry scancode maps
•     Disabled all overlays (Xbox Game Bar, NVIDIA, etc.)
•     Toggled GPU Performance on/off
•     Toggled Real-Time Drawing & Editing
•     Toggled Pixel Preview, Overprint Preview, Smart Guides, Rulers / Reset Preferences 
•     Tested in blank documents and new files
•     Disabled Creative Cloud sync features
•     Checked for background processes
•     Verified no cloud sync spikes
•     Tried all workspaces and UI scaling
•     Disabled all plugins
•     REINSTALLED Illustrator twice
•     Restarted Windows about a dozen times
The freeze is almost perfectly rhythmic, which makes me think something is interrupting Illustrator’s input or GPU  on a timer. But I cannot find the culprit. The only thing i havent done is completely wipe Creative Cloud and delete all the file/ Reinstall. 
Important details:
•     The freeze happens even with nothing selected
•     The freeze happens in a blank document
•     The freeze does NOT affect other apps
•     The freeze does NOT affect the mouse or system — only Illustrator
•     GPU Preview vs CPU Preview makes no difference
•     No recent hardware changes
•     No new peripherals
•     No new drivers installed before this started
At this point, it feels like a deeper Illustrator subsystem issue — possibly input polling, GPU fallback, or a background Adobe process firing on a fixed interval.
Has anyone seen this exact rhythmic freeze before?
Is there a known issue with a recent update?
What else can I check that isn’t on the usual “reset prefs” list?
Any help from Adobe staff or power users would be appreciated — i feel like ive run into this issue in the past but it was much much, less noticeable. It prompted me to go through the rabbithole this time since it was making the workflow unenjoyable. 

Thanks.