High CPU usage by dwm.exe when you use the Magnifier through RDP to a Windows 10 computer

Applies to: Windows 10

Symptoms


When you use the Magnifier app on a remote Windows 10-based computer through a Remote Desktop Protocol (RDP) session, the CPU usage of the dwm.exe process spikes.

This issue occurs when smoothing is enabled in Magnifier. This feature is enabled by default in Windows 10.

Cause


This issue occurs because RDP uses the software renderer. The software renderer uses the CPU to run graphics commands.

Resolution


To improve performance, disable smoothing in the Magnifier app. To do this, open the Settings app, select Ease of Access, select Magnifier, and then clear the Smooth edges of images and text check box.

Setting for Magnifier