"slowness" wasn't the point. Nobody expects a 512 MB RPi to be responsive as a Moodle server. The point was, the current MoodleBox, 4.7.0, won't start at all on a Pi 2 W or Pi 3 A+. I tested in a haste, can recheck. If it is intended, then those models need to be taken out of the list of supported models. My hope was, by raising the swap to 512 MB MoodleBox will at least start, albeit very slow.
There is a difference between being very slow and not starting at all!