Fix for Electron Tahoe GPU slowdown bug in Slack and Discord updates
The recent slowdown experienced by popular applications like Slack and Discord has left many users frustrated, especially after Apple released the macOS 26 Tahoe update. This performance issue stemmed from an underlying bug within the Electron framework, causing significant lag and sluggishness. Fortunately, updates have now been rolled out to address these concerns, but understanding the root of the problem provides valuable insight into how software interacts with operating systems.
The origin of the Electron and Tahoe slowdown
Electron has become the go-to framework for developers looking to create cross-platform applications due to its convenience. Utilizing web technologies such as HTML, CSS, and JavaScript, developers can easily write code once and deploy it across multiple operating systems, including macOS, Windows, and Linux. However, this very convenience can lead to complications when Electron interacts with the native windowing systems of these platforms.
Historically, Electron used a private AppKit method called _cornerMask to manage window rounding and shadow effects on macOS. While this workaround functioned effectively for years, it was never part of Apple's official API. The introduction of macOS Tahoe in September 2025 brought about significant changes in how the system renders windows. These changes, designed to enhance the "Liquid Glass" aesthetic with transparency and dynamic shadows, inadvertently exposed the limitations of the Electron framework.
As Tahoe's new rendering pipeline came into play, the hidden override used by Electron clashed with these updates, triggering performance issues that left users noticing their machines running slowly, particularly after long usage of affected apps. Actions that were once seamless, like window switching or scrolling, became noticeably laggy, leading to increased fan activity and frustration among users.
Understanding the fix for the slowdown
Upon investigation, it became clear that every visible application window prompted the WindowServer to repeatedly redraw shadows, consuming unnecessary GPU resources and resulting in a noticeable drop in system performance. This GPU load could go unnoticed in standard performance monitoring, but users reported significant lag when using applications like Slack and Discord. Interestingly, minimizing these apps restored smooth operation, indicating that they were the source of the issue.
The Electron maintainers acted swiftly once the problem was identified. They removed the problematic _cornerMask override and reverted to macOS's standard rendering path. However, the implementation of these changes took some time as app developers needed to update their applications to the new versions of Electron.
Applications that have received the necessary updates
The swift action taken by Electron's maintainers has led to significant improvements in several high-profile applications. The removal of the flawed rendering code stopped the continuous redraw loop and allowed the WindowServer to function normally again. The fix has been incorporated into the following Electron versions: 36.9.2, 37.6.0, and 38.2.0.
- Updated: Slack
- Updated: Discord
- Updated: Figma
- Updated: Visual Studio Code
Users who have updated to the latest versions of these applications should now experience normal performance levels on macOS Tahoe, eliminating the lag issues that previously plagued their experience.
Applications still impacted by the bug
Despite the progress made, several notable applications remain on older versions of Electron and may still contribute to GPU spikes within the WindowServer, leading to continued sluggishness. These include:
- Not updated: 1Password
- Not updated: Dropbox
- Not updated: Bitwarden
- Not updated: Postman
Until these applications are rebuilt using the patched versions of Electron, users can expect a similar experience of lag and performance issues when these apps are running.
What users can do to mitigate performance issues
While users cannot directly resolve the underlying issue themselves, they can take several steps to minimize the impact of the slowdown until app developers implement the necessary updates:
- Check for updates: Regularly update applications to ensure access to the latest fixes.
- Monitor GPU load: Use Activity Monitor to check GPU usage; high usage from WindowServer when running an app indicates that the app may not be updated.
- Limit app usage: Minimize or close apps that are known to be problematic when they are not in use to reduce GPU strain.
- Disable transparency: If possible, reduce visual effects such as transparency in macOS settings to decrease GPU load.
While these workaround methods may temporarily alleviate some performance issues, they do not address the core problem. Ultimately, the best solution lies in keeping applications updated to the latest Electron versions, allowing users to return to a smooth computing experience.
Once the patched Electron version is installed, users will notice a significant reduction in GPU activity, restoring the performance of their applications to baseline levels. As development teams work to implement these changes, staying informed about updates will be crucial for a seamless user experience.
For those looking for more tips on optimizing performance on macOS, check out this helpful video on improving speed on your Mac:
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