Extreme mouse lagging in Illustrator & indesign

Hi @lisajacobs,

Sorry about the trouble. I was able to replicate the weird square issue at my end. I have shared the details & screen recording with the team. I would also suggest you post this on our UserVoice page and share the link of that UserVoice here so other people can UpVote it and stay tuned for the updates.

For your lagging issue on external monitors, could you please share a few details like:

• Screenshot of “About This Mac” (both Overview and Displays tab).
• With which port and cable combination it is connected.
• What is the scaled/ default resolution of your Macbook screen & external monitors?
  (Note: When you hover your cursor/ mouse over the scaled or default resolution, you will see the exact resolution as highlighted in the screenshot below)
  
• For just testing sake, could you please check if setting the scaled Display resolution as 1920 x 1080 or below from the System Preferences help resolve the issue?
  
  

I will be looking forward to your response.

Thanks & Regards,

Anshul Saini

Mac OS has this automatic graphics switching. Can you turn that off?

Are you using Pixel Preview? This can force the use of CPU instead of GPU as well.

Sorry, I know it's frustrating! Not what you want to see with such a powerful computer. I can see by looking at the file tab that you are in CPU preview instead of GPU, which means Illustrator is not using the graphics card, so you are seeing that lag. You can switch by going to View > View Using GPU  - and in Preferences under Performance you can enable GPU and at the bottom check Real-Time Drawing and Editing. This should all be turned on by default. This switch to CPU may have just happened without anything on your part. It's also causing the little gray box, which I think is a smart guides label that doesn't work in CPU.

I've experienced this myself - it was related to having a 2nd monitor and an earlier update to Illustrator that kept switching to CPU. Hopefully if you switch back to GPU it will resolve, but if it persists, you may need to go through all the troubleshooting steps like deleting preferences, restarting Illustrator and the mac. And after that maybe uninstall/reinstall.