When opening a new explorer window, there is a long lag time before the the new file browser appears.
I put ProcMon on it, and in the slow sections the following registry key access happens over and over:
RegQueryKey HKCU SUCCESS Query: HandleTags, HandleTags: 0x0
RegOpenKey HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\PostBootReminders\Microsoft.NetDriveReconnectFailed SUCCESS Desired Access: Read
RegCloseKey HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\PostBootReminders\Microsoft.NetDriveReconnectFailed SUCCESS
After reading the contents of Microsoft.NetDriveReconnectFailed
, there is a HALF SECOND delay, 0.5 to 0.6 sec, then the above keys are queried again. The below plot shows all the procmon events recorded and the time between events. The time consuming vertical jumps in the plot are where the above registry keys are queried.