Path of Exile saturates GPU 3D queue when unfocused - severe Windows lag

Path of Exile uses 100% GPU 3D when unfocused - Severe Windows lag (web browser tabs slow, typing delay) unless Background FPS is capped


Summary
Starting a few days ago, Path of Exile began consuming 100% of my GPU’s 3D engine even while the game is running in the background (alt-tabbed). This causes major system-wide slowdown:

• Chrome takes several seconds to open a new tab
• Typing outside the game becomes extremely laggy
• Windows desktop animations stutter
• DWM.exe (Desktop Window Manager) starves for GPU time
• Other desktop apps become unresponsive
• Issue disappears instantly when capping Background FPS

CPU sits around 35–40%. RAM is normal.
Only the GPU’s 3D engine is pinned at 99%.

The issue is 100% reproducible and was not happening previously with the same settings.

Workaround that fixes everything instantly
Setting Background FPS = 30 immediately resolves all desktop lag.

This strongly suggests PoE is saturating the GPU’s 3D queue while unfocused, preventing Windows from rendering normally.

Steps to Reproduce
1. Launch Path of Exile
2. Set Background FPS to Unlimited
3. Alt-tab out of the game
4. Observe GPU 3D usage instantly hit 99%
5. Chrome becomes extremely slow, typing lags, desktop stutters
6. Set Background FPS = 30
7. Problem disappears immediately

System
• RTX 4080
• Windows 11
• Multi-monitor setup (one HDR, one SDR)
• Latest Nvidia drivers
• No CPU/RAM bottleneck
• Issue only occurs when PoE is running

Notes
This behavior started recently, so it may be related to:
• A recent game patch
• A Windows update
• Multi-monitor/HDR interaction with the game engine

Posting here so GGG is aware and so other players experiencing desktop lag can find the fix quickly. Background FPS cap resolves the issue, but it appears the game is consuming exclusive GPU scheduling time while unfocused.

Thank you.