Descriptive Problem Summary:
Dream Seeker crashes in a render loop when using `VIS_HIDE` on viewports to view other Z levels that also have viewports to the Z level you are on, when simulating mobius strip worlds.

Numbered Steps to Reproduce Problem:
- Create multiple Z levels
- Create viewports to refer to the connected Z levels in each direction of the map (8, 4 cardinal and diagonal)
- Enter the view of the viewports
- Dream Seeker slow down and crash

Code Snippet (if applicable) to Reproduce Problem:


Expected Results:
No Dream Seeker crash.

Actual Results:
Dream Seeker slows down and crashes.
https://cdn.discordapp.com/attachments/725458598213451879/ 1137101975733932043/2023-08-04_22-16-14.mov

Does the problem occur:
Every time? Or how often? Yes
In other games? Yes
In other user accounts? Yes
On other computers? Yes

When does the problem NOT occur?
When viewports are not used.

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit http://www.byond.com/download/build to download old versions for testing.)
Yes

Workarounds:
Not using viewports, otherwise none that I have discovered.