CGPDFService hogging my CPU

You can stop CGPDFService from hogging your CPU by excluding your hard drive or folders containing large PDF collections from Spotlight indexing via System Settings > Siri & Spotlight > Privacy.

Why is this happening?

• CGPDFService is a background process introduced in macOS Sonoma that handles reading and parsing text inside PDF files so Spotlight can index them.
• It triggers high CPU or memory usage when Spotlight gets stuck in a loop trying to parse corrupt PDFs, a massive library of documents, or files on a connected network/external drive.
• Force-quitting the process in Activity Monitor does not work because macOS immediately restarts it as long as the indexing queue is active. 

How to stop it

• Exclude your drive or specific folders:
  • Open System Settings.
  • Click Spotlight.
  • Scroll down to the bottom and click Spotlight Privacy...
  • Drag and drop your main Macintosh HD or specific folders heavy with PDFs (like Documents or Downloads) into the exclusion list.
  • More info: Prevent Spotlight searches in specific folders or disks – Apple Support

• Disable PDF search results:
  • In System Settings > Spotlight, scroll to Results from System, click the (i) next to the Files toggle and toggle off PDF Documents to reduce search processing.

If that doesn’t work, Copy/Paste this into Terminal. sudo will ask for your password. Just type the password and hit return. It won't show anything on screen. Those two commands essentially nuke all the Spotlight records then force a reindex. You may need to restart or log out/in after running the commands.

sudo mdutil -X /; sudo mdutil -i on /