There is a long delay, with a black screen, lasting about 30 seconds, between boot progress bar and terminal manager screen (or login panel).
The terminal is attempting to write config program code to magnetic stripe reader but reader is hung up. This causes multiple retries delaying the boot cycle.
There are three possible solutions to this problem, in order of simplicity:
1. unplug / replug keyboard and reader from terminal
2. unplug / replug power cord from terminal
3. replace reader