I checked the launch of the latest version with the Bullsey XFCE EDGE kernel using a USB flash drive connected to USB 2.0. The startup time before the login screen saver appears is about 70-80 seconds. Not bad for an old USB stick and a slow USB 2.0 port. 
for the sake of curiosity, I recorded the latest version of manjaro on a USB flash drive, connected it to Quartz64, the system started up and works fine completely from USB media. I.e., can very quickly switch from Armbian (which is installed on eMMC with a new u-boot that supports launching from USB media) to any system on USB media for work or testing.
for the sake of curiosity, I recorded the latest version of manjaro on a USB flash drive, connected it to Quartz64, the system started up and works fine completely from USB media. I.e., can very quickly switch from Armbian (which is installed on eMMC with a new u-boot that supports launching from USB media) to any system on USB media for work or testing.