High CPU usage when downloading messages from Gmail

I'm on Fedora Workstation 35 and use Thunderbird with my Gmail account. I've noticed that whenever it attempts to download messages in the background, my CPU absolutely spikes and it's literally the only time when using my laptop that my fans kick on. If I close Thunderbird and open it back up, it's fine for about 5 - 10 minutes before repeating.

I looked around and couldn't find any recent articles or bug reports (newer than 2018) discussing this issue. I did follow a performance recommendation and set the mail.db.idle_limit to 30000000.

Is anyone else seeing something similar on Fedora or other Linux flavors? For what it's worth, I never experienced this issue on my old 2013 MacBook Pro running macOS Big Sur.