I do find on simple presets with only a few blocks it's quite instantaneous, like factory 05c to 06c (still on firmware 1.04 here).
Presumably the less it has to load the quicker it is, and using the same path and block layout seems to be a factor. Wondering if only using say 6 mono blocks which one dsp can easily handle, it's a bit quicker loading if you split the blocks between both dsps. For instance, Volume pedal, wah, compressor, amp on path 1, output to path 2a for delay, reverb. I don't need a lot for my 8 basic do all coverband presets. Bottom row, Clean, dirty clean, drive, heavy rock, then top row big lush clean, Cleanish solo, big solo minus a few db, big solo. Then a few specific song presets. Seems as though keeping say the reverb block settings the same in each preset, with varying mix, and in the exact same position (say position 6 on 2a) also helps, but I maybe imagining things!