Microsoft’s admission that KB4559309 caused the boot to slow down is currently under investigation.

After the KB4559309 cumulative update was automatically deployed, many Windows 10 users complained that the PC’s power-up time was significantly longer. The issue has been reported to many users on social media and the Microsoft support community since June, and now Microsoft has acknowledged and begun investigating the issue.

Microsoft's admission that KB4559309 caused the boot to slow down is currently under investigation.

The KB4559309 is a cumulative update for The Edge browser, with user feedback in late June slowing down the computer’s boot. In addition, when Windows 10 loads after a patch is applied, some people notice that their pc is moving more slowly than before, especially when the FPS drops when loading applications, switching applications, or playing games, with significant delays or lags.

Microsoft's admission that KB4559309 caused the boot to slow down is currently under investigation.

To make matters worse, one user pointed out, “Since I installed this update, I’ve had startup issues and can only start in safe mode.” Windows Startup Repair says it won’t fix the problem.” Other users have similar complaints.

Now Microsoft has finally acknowledged the problem. “I’ve spoken to Missy Quarry of the Edge team and they’re looking into it,” said one forum moderator in the Microsoft community. However, they do need more details to investigate, and users with this problem can submit it through Feedback Hub on Windows 10.”

Microsoft's admission that KB4559309 caused the boot to slow down is currently under investigation.