I've read that it should be possible to push the SE/30 to its maximum RAM capacity with eight pieces of 16 MByte, 30-Pin SIMMs. I've never seen such a machine in the wild. Neither with 64 or 80 MB. Memory test takes a notable amount of time when having 16/20 MB RAM in it. I wonder how long a memory test with full blown 128 MB would take. I'd prefer first-hand real-world measures with a stop watch, not a theoretical calculation.
I maxed out an SE/30 in the early 90s, adding max RAM, external SCSI drives, and a huge grey scale display. I must have installed a third party video card, I just checked, and the SE/30 didn't have built-in 2nd display support. I think I was still using Object Pascal and MacApp back then. The machine took long enough to boot that I would power up the drives and CPU then go get a cup of coffee. I was only 30 feet from my coffee machine, and the machine would be ready when I got back, so no more that 2 minutes, for sure.
The SE/30 was probably the finest tiny screen mac ever made. I was also really fond of the quadra 605 that I replaced it with, an excellent 'mac mini' that was only about as big as 4 of the modern minis ... maybe 16" x 14" x 2.5".