Bug#870628: Please warn about slow starts on USB
I recently installed form scratch a Stretch to an old computer using an USB
The "boot menu" show and I hit enter for "Graphical Install". And then I
though it crashed. Twice. The keys don't make the menu move. Caps lock key
It actually took 2'10" to show next menu "Select a language".
I believe section "5.1.1 Booting from USB Memory Stick" should warn
about possible big delays.