This may or may not be relevant to your issue, but I discovered some things while troubleshooting yesterday that I strongly suspect have been a major cause for the sluggishness & memory usage I've been experiencing. Though these may also be Mac-specific.

1. Despite having reset preferences multiple times over the last few months & years, and despite having ran Adobe Cleaner + uninstalled + reinstalled all Adobe apps, there were a number of very old/obsolete Adobe files on my system:
• Obsolete files in /Users/Shared: This contains the folders: Adobe, AdobeGCData, AdobeGCInfo, NGL. I deleted /Users/Shared/Adobe/NGL/.VU1JUmFuZG9tR3VpZEluY2FybmF0aW9u.dat and /Users/Shared/NGL/.VU1JUmFuZG9tR3VpZA.dat
• Obsolete hidden files in ~/Library/Application Support: The "last modified" dates on these ranged from 2022 to 2025. They included: .ACCC_Lock, .ADCS_Lock, .CCH_GrowthSDKHelper_Lock, .CCH_NGLW_Lock, CCH_UpdateNotifier_Lock, .CCH_UPI_Lock, COSY_Lock. I deleted all of these.

2. Despite having granted full disk access to Creative Cloud, Illustrator, Indesign, and Photoshop, it seems Creative Cloud and/or associated apps did not have the permissions they wanted, and so were stuck in some kind of feedback loop where they made continuous failed attempts to reach Adobe servers. I am very opposed to granting so many far-reaching permissions, however I did methodically grant additional permissions to every possible Adobe app to try to resolve these issues. I granted the below permissions to any Adobe apps/services that weren't already added.
• Full Disk Access
• App Management
• Local Network

I've had this issue for a long time. It doesn't happen on a fresh restart and open of the app. Its something that begins to happen only after interacting with something - don't know what. But once it starts, it sucks the life out of my machine until I reload the app. Currently using v30.0.

Still an issue with macOS 26.4 (Tahoe) and Illustrator 30.3 (Updated 6 days ago). I was wondering why my Macbook Pro M4 was so slow and Activity Monitor was showing Illustrator using CPU sustained, idle and no documents open at 100%+.
I do let my Macbook Pro sleep but that should not be an issue in 2026??

I'm seeing the same with Illustrator 29.8.2 on macOS 26

Constantly high CPU usage and sluggish performance even in simple documents

At this point I think Illustrator for mac is in desperate need of a full rewrite

I have the same issue on 2 different Macs. Both are on the current versions of Illustrator. This has been going on for about the last year.
Illustrator will consume 100% CPU with nothing open. M1 machine gets hot. Seems to be a memory leak.