My '07 M3 has a retrofitted CIC, and that took close to a minute I would say for the update.
But in my wife's '11 X3 it was lot quicker more like 30 sec. There are no difference to the respective updates. The screen messages are the same.
I think if the USB must be formatted with FAT, not NTFS. for the car to see and read the update file.
2007 E92 6MT - Silverstone II with /// Performance Exhaust with ACM Test Pipes and BPM Sport Stage II Dev-Tune - Proper engine warm up, 12-monthly oil change, Castrol TWS 10w-60
2014 F15 X5 3.0d