Electron performance issue on MacOS Tahoe (override of cornerMask Appkit Private API)

[gsiemon]

System details:

MacBookPro M3 Max
MacStudio M1 Ultra

Positron and OS details:

Affects versions of Positron using Electron versions <37.6.0 (current Positron release is 37.2.3)

MacOS Tahoe (all versions) - currently installed version 26.0.1

Currently installed Positron version:
Positron Version: 2025.10.1 build 4
Code - OSS Version: 1.103.0
Commit: b13dd1c
Date: 2025-10-14T21:43:42.876Z
Electron: 37.2.3
Chromium: 138.0.7204.100
Node.js: 22.17.0
V8: 13.8.500258-electron.0
OS: Darwin arm64 25.0.0

Session details:

Does not depend on session

Describe the issue:

Electron apps running on MacOS Tahoe, using Electron versions prior to v38.2.0, v37.6.0 and v36.9.2 override an Appkit Private API _cornerMask which results in high GPU usage by the WindowServer process resulting in degraded performance.

Electron has fixed the issue in the above versions. Applications using Electron need to be updated to include the fix.

Reference:
electron/electron#48311
https://mjtsai.com/blog/2025/09/30/electron-apps-causing-system-wide-lag-on-tahoe/

Steps to reproduce the issue:

Install MacOS Tahoe and use any Electron based application with Electron versions less than v38.2.0, v37.6.0 and v36.9.2.

Expected or desired behavior:

WindowServer GPU utilisation is not affected when Electron apps are used.

Were there any error messages in the UI, Output panel, or Developer Tools console?

None

[nstrayer]

Hi @gsiemon,

We are aware of this (frustrating) problem. The good news is that upstream VSCode has already fixed this in version 1.105 by upgrading to Electron 37.6.0.

We're currently working on updating Positron to the latest version of CodeOSS and which will address this.

We appreciate your patience as we get this updated!

[juliasilge]

Related to #10068

[juliasilge]

When we confirm that 1.105.0 is integrated, we can also resolve this issue.