Let me put down my thought process: You have to start to think of designing a 6-slot x8-len vector pipeline doing 48 hashes in parallel first which needs at least 10 steps —- if you convert three stages to multiply adds and do parallel XORs for the other three) —- the problem with 10 cycle hashing is you need to cram 96 scalar xors along side your vector pipeline, so that will use all 12 ALUs for 8 of those cycles. Leaving you only 24 more scalar ops per hash cycle which isn’t enough for the 48 tree value xors..

so you must use at least 11 steps per hash, with 96 xors (including the tree value xor) done in the scalar alus using 8 steps, and giving 3*12 Alu ops per hash cycle. You need 12 more ops per hash to do odd/even, so you must be 12 stages, and just do all of the hash ops in valu, 4 cycles of 12 alus doing modulo, 8 cycles x 12 alus free

With 12 steps and 48 parallel you’re absolute minimum could be 4096/48 x 12 = 1,024 cycles, since stage 10 can be optimized (you don’t need the odd/even modulo cycle, and can use some of those extra scalar cycles to pre-xor the constant can save you ~10 cycles. 1024 gonna be real hard, but I can imagine shenanigans to get it down to 1014, sub-1000 possible by throwing more xor to the scalar alus.