you can check the log and see if there is anything causing it.
right click this pc and choose manage or right click start, choose run and enter compmgmt.msc
expand event viewer/ application and service logs/ Microsoft/ windows/ diagnostics-performance/ operational
check the boot performance monitoring entries, see if any are critical.
if not, you can still check the individual entries. just click to highlight and then in the lower pane, select the details tab.
look for anything taking a long time. the durations are in milliseconds, so add a decimal 3 places from the right to get the number of seconds