Most of the time we&#x27;re iterating through a cyrus.index, where there&#x27;s 104 bytes per record, and we&#x27;re doing a CRC32 over 100 of them, or we&#x27;re reading through a twoskip database where we&#x27;re CRCing the header (24+bytes, average 32) and then doing a couple of mmap lookup and memcmp operations before jumping to the next header, which is normally only within a hundred bytes forwards on a bit and mostly sorted database.  The mmap lookahead will also have been in that close-by range.<p>Also, our oldest CPU on production servers seems to be the E5520 right now, which has 128kb of L1 data cache.