If you tried to add a lot of files to the Start Menu in Windows 10, you probably noticed that the Start Menu starts lagging if there are a lot of files. Recently, some users reported that the Start Menu starts to lag if you add more than 512 files to it. Additionally, adding more than 512 items to the Start Menu will also cause some apps to disappear from the All Apps list on the Start Menu.
Yes, the bug is present on the public release of Windows 10 (build 10240). Nonetheless, this is indeed a pretty odd bug, which a lot of users may not face but this could be a major issue for some.
If you want to test the issue, you can do so by creating a folder on the %appdata%MicrosoftWindowsStart Menu directory and pasting shortcuts of more than 512 images. Keep in mind that this may cause the Start Menu to completely stop working, so we recommend checking out the bug on a Virtual Machine.