Michael Tsai – Blog – Electron Apps Causing System-Wide Lag on Tahoe

ToxicLand (via Hacker News):

Using an M1 Max MacBook Pro, having Electron-based apps open / not minimized causes a huge lag.

CPU and GPU usage remains low, but if I have Discord and VS Code open, moving windows, scrolling is stuttery. It happens even when only Discord is open but it gets worse if I open a second Electron app.

This is kind of weird because while having Discord open and I’m in Chrome, the lag still occurs, but it’s fixed if I minimize.

avarayr:

After a lot of digging, I believe I’ve found the root cause of the WindowServer GPU spike on macOS 26 when shadows are enabled.

It turns out Electron was overriding a private AppKit API (_cornerMask) to apply custom corner masks to vibrant views.

This method is called by WindowServer to calculate the shadow of the window. I’m speculating that Apple uses some sort of memoization by reference, and this method breaks the memoization and forces WindowServer to repeatedly recalculate and repaint the shadow.

🤔 What’s particularly funny is that even a simple override that does nothing but call super still presents the issue.

Previously:

Update (2025-10-01): Tomas Kafka:

This script detects apps with not yet updated versions of Electron.

See also: Hacker News.

Update (2025-10-06): shamelectron (via Hacker News):

Tracking problematic Electron apps macOS Tahoe.

Craig Hockenberry:

I took that script, updated some parts that required Xcode to be installed, and wrapped it up in an Apple Script applet that’s easy to download and run[…]

[…]

We’re hearing from customers that some of our apps are running slowly on Tahoe and I suspect that this bug has something to do with it.

Update (2025-10-14): Michael Burkhardt:

Now, the Electron team has fixed the issue, and said fix is beginning to roll out in popular third party apps that utilize the framework.

[…]

There are also a lot of major apps that haven’t yet updated their Electron version, including 1Password, Bitwarden, Cursor, Dropbox, Windsurf, and more. You can check out the tracker for a more comprehensive list.

Cocoa Cursor Discord Electron Mac macOS Tahoe 26 Private API Visual Studio Code

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