AnyDesk's render performance is highly dependent on the graphics card. If AnyDesk suddenly slows down for no apparent reason, check with the Process Hacker tool whether another program occupies too much GPU resources. For example this happens when there is a HD video playing in chrome while an AnyDesk session is running. You can free the GPU for AnyDesk by going to full screen mode or by minimizing the window of the application that occupies the graphics processor.
You can go to full screen mode by selecting "Full Screen" in the main menu during a session.
By default, AnyDesk uses a Direct 3D-Renderer. If you have problems with the display, try selecting a lower rendering mode in the options tab. First, try Direct Draw. If this does not help, you can disable hardware acceleration. This is not recommended and AnyDesk's performance will be cut back severely.
In Windows XP only Direct Draw output is available.