Trying to do do viable comparisons (see https://lightillusion.com/forums/tips-tricks-17/colourspace-lut-size-1425-2.html#newreply), I have launched very large profiles based on Virtual Probe:
I have run:
1. 17 cube/14 Bcc. It has taken around 20/25 minutes o finish (around 5000 patches)
2. 33 cube. It has taken 09 hours and 41 minutes (around 40000 patches)
3. 66 cube. Still running after one day. As all the profile it has started at a very good pace, but start lowering more and more after around 2500 patches. Now after 71100 patches (out of 280796) each patch takes 2 seconds (It looks I have to wait al least for 5 days, but I am not so optimistic due to fact the pace decrements with the measured patches number)

Off course these execution times depend on my PC performance, but, as there is not linearity in the patch pace, I think there is something either to improve, eg having a fast profiling mode (WIBINI) or to fix (bug)

Yes, that will be the case.
Such HUGE patch sets will take basically forever due to the increasing overheads.
You will likely run into Windows memory issues too.
And the results will virtually always be suboptimal due to the spacing granularity of the patches...

Steve

You have given us the bike (>21 cube), but not a way to ride it
Anyhow, seriously, is that increasing overhead coming only from insertion of values at the end of a sequential file? I understand there are a lot of more stuff done my CS, whose computing size depends on the previous patches. A solution to optimise that is wished by many of us, I think.

A suggestion: I am trying to understand the advantage of increasing the LUT level, based on machine based speculation.
My minimum LUT level is 33. So I have based everything on comparing the outcome at 33 with the one at 66.
Any way I can have a minimum lower level?

No - the aim was to provide Large LUTs, not excessive profiling sizes.
Using excessive large patch sets will never work well.
But having larger Grey Axis Sizes does make sense.

And going below 33 for a LUT size would be rather pointless, so no, you can't do that.

Steve