WT causes the whole Windows animation to be super laggy (after RDP?), until all the WT processes are terminated

Windows Terminal version

1.21.3231.0

Windows build number

10.0.19045.5247

Other Software

Command line

Steps to reproduce

There are no concrete steps to reproduce, as the issue occurs randomly. However, I’ve noticed two recurring patterns:

1. Using RDP to access this computer often triggers the bug later when I use the computer locally (though not always immediately).
2. Having multiple Windows Terminal (WT) windows open for an extended period.

Expected Behavior

It shouldn't cause Windows animation lagging issue.

Actual Behavior

I briefly mentioned this performance issue [in another ticket](https://github.com/microsoft/terminal/issues/17414#issuecomment-2539085553), but I believe it deserves its own standalone discussion.

When the bug occurs, the entire Windows desktop UI becomes extremely laggy (e.g., dragging and switching windows), with performance dropping to what feels like less than 20 FPS. 3D applications like full-screen games are not affected; only the desktop UI.

To resolve the issue, I must close all open Windows Terminal windows (I typically keep 2–3 open at any given time). Doing so immediately restores normal performance.

The issue is not tied to any specific tab—I’ve tested this by opening a new window and then closing all existing windows, but the problem persists.

Here’s what the processes related to WT look like before I terminate them (and fix the issue):

No source file, test, or entry point is named. Start by investigating the Windows Terminal process behavior under the reported conditions: RDP access, multiple long-lived windows, and the resulting desktop animation lag. Done would require identifying a reproducible cause and demonstrating that closing Terminal processes is no longer needed to restore normal performance.