Optiplex 7050 MFF, Windows 10 1803, Very slow boot

Hi,

We have a number of Optiplex 7050 Micro with:

Intel i5-6500T

8GB RAM

256GB SK Hynix SC311 SATA HD

They were recently updated to the Spring Creators Update (1803) of Windows 10.  Prior to this they were running the Fall Creators Update (1709) and on that version the boot time from power on to the desktop was around 30 seconds.  Since the update to Windows 10 1803 the boot time has increased to 4 minutes and 30 seconds.  I have tried updating the drivers and BIOS from the support page using the support assistant which has not fixed the issue.  The computers are also running the latest build from Windows Update, version 17134.81) which has not fixed the issue.  Why are these computers booting so much slower on the latest Windows 10 update and how do we fix it?

Thanks.