What is too slow? Are there ramifications for printing too slow? There is a speed control knob on my Prusa i3 that I adjust when the time between layers drops below a few seconds. There is a speed setting for this in slic3r but I’m not quite sure what criteria to optimize for or what might be a good starting point.
Possible ramification of printing extremely slowly is that you’d grow old and expire before the print finishes. At less ridiculous fractions of full speed (tens of minutes per layer) you might have layers being too cold for the hot extrusion being put on top of them. I’ve found detail to be better maintained at slow speeds. Ooze can be a consideration.
1mm/s is a rough ballpark of minimum speed. If you drop below that, your hotend will have a hard time controlling its plastic flow - you’ll essentially be printing with its ooze.
Printing too slowly could allow the melt zone to creep up the hot end, resulting in crystallised PLA towards the top of the tip. Not good.