Unfortunately, it is not possible to reduce this time. Usually when WMI is corrupt, Lansweeper will detect it much quicker, however, when scanning takes longer than 2 hours, the scan is aborted and it is assumed that the WMI is corrupt. I recommend going through the following knowledgebase article and trying again.
https://www.lansweeper.com/kb/47/How-to-repair-a-corrupt-WMI-installation.html