I experience the same issue, I found that my bigbox tooks around 2mins to startup with my desktop (i9 9700 and 1080Ti 16G DDR4 ) , however when I bring my bigbox to my company and it only took a few sec to launch, they both are same and my company's desktop is much worse than my home one.
From this point, I test a lot (rebuild system, change SSD, ect) but It still not working.
Besides that, I found retroarch also took different startup time.