[Bug] Browser deadlocks when restoring large session (~400 tabs) on Chromium 146.0.7680.80

[stemalomd]

Description

When restoring a large session (~400 tabs) via Tab Session Manager, the browser eventually
deadlocks: tabs turn black, then the entire browser freezes (0% disk, CPU stops fluctuating).

The browser's native "Restore previous session" does not trigger this issue.

Importantly, TSM's lazy load is already enabled — meaning only 1 tab per window actually
loads content at a time. The ~400 other tabs are created but discarded (not rendered).
This rules out resource exhaustion from simultaneous rendering as the cause.

Timeline

• Chrome: Issue first appeared around November 2025, still unresolved.
• Brave: Issue appeared after an update sometime between 2026/3/11 and 2026/3/15.

Steps to Reproduce

1. Enable lazy load in Tab Session Manager settings.
2. Save a session with ~400 tabs.
3. Open a fresh browser window (Chrome or Brave 146.0.7680.80).
4. Restore the session via the extension.
5. Browser begins creating tabs → after a short while, tabs turn black → browser freezes entirely.

Environment

• OS: Windows 10 Enterprise 22H2
• Failing: Chrome / Brave 146.0.7680.80 → Deadlock
• Working: Microsoft Edge 146.0.3856.59 (older Chromium build) → No issue

Troubleshooting Already Attempted

• Lazy load: already enabled (only 1 tab loads content per window)
• Reduced session size from 600 to 400 tabs
• Changed ANGLE backend to D3D11
• Disabled other extensions