Quick Answer

Lag and pixelation are almost always caused by a weak or unstable internet connection on one or both devices
Your Mac going to sleep mid-session can also cause dropped performance

📶 Check Your Connection First

Workbench streams your Mac's display in real time, so a strong and stable internet connection on both ends makes a big difference. A weak signal on either your Mac or your iPad/iPhone is the most common cause of lag and pixelation.

Try the following:

Make sure both your Mac and your iPad or iPhone are on a strong Wi-Fi connection
Move closer to your router, or switch your Mac to a wired Ethernet connection if possible
Restart your router if your connection has been unreliable
Avoid using Workbench on a hotspot or cellular connection if possible. While supported, these can become too unstable for a smooth session if you have a bad connection

😴 Is Your Mac Staying Awake?

If your Mac goes to sleep during a session, Workbench will struggle to maintain a connection. Make sure sleep prevention is enabled.

To check:

Open Workbench on your Mac
Click the ... next to your computer name
Select Remote Access Settings
Make sure Prevent Sleep is turned on
You can also check this in macOS System Settings > Battery/Energy > Turn on “Prevent automatic sleeping when the display is off.”
Optional: To keep the screen from turning off, go to Lock Screen in the sidebar and set "Turn display off on power adapter when inactive" to Never.