[ilyapt]

go test -run '^$' -bench . -benchmem -count 3 ./book, Apple M3 Pro, Go 1.26, medians of 3 runs, ns/op, 0 allocs/op everywhere.

Blocked side (blocks of 128 entries behind a chain of block keys) vs a flat sorted slice of the same entries with the same gallop search. Bid side, best price at the end.

scenario	levels	blocks	flat
lookup at a uniform random price	100	27.7	26.9
lookup at a uniform random price	1 000	44.6	43.1
lookup at a uniform random price	10 000	67.2	64.9
lookup at a uniform random price	50 000	85.2	96.0
lookup within the 10 best	100	15.4	15.2
lookup within the 10 best	1 000	15.3	15.2
lookup within the 10 best	10 000	15.3	15.2
lookup within the 10 best	50 000	15.4	15.2
remove + insert within the 10 best	100	40.8	39.4
remove + insert within the 10 best	1 000	40.9	39.9
remove + insert within the 10 best	10 000	40.9	39.8
remove + insert within the 10 best	50 000	40.8	40.8
remove + insert at a random depth	100	84.0	82.4
remove + insert at a random depth	1 000	116	264
remove + insert at a random depth	10 000	166	1 997
remove + insert at a random depth	50 000	210	12 395
best price	any	1.1	0.5
walk the 10 best levels with a cursor	1 000	8.2	8.0
walk the 10 best levels into a buffer	1 000	9.4	8.0
walk the 50 best levels with a cursor	1 000	34.3	31.3
walk the 50 best levels into a buffer	1 000	34.7	31.3