The census pread 10 bytes per frame -- an O(frames) syscall floor, ~150k calls on tk (#121). A 64KB read-ahead window keeps the walk a measured physical pass at ~1/40th the syscalls, and the config/roll read adopts the scan index like every other cached verb. tk stat: 0.234s -> 0.026s, now ahead of fossil info. Output byte-identical. check-in: c17e0233ca user: dmestas tags: trunk