Hex Fiend uses an optimized Boyer-Moore search routine that relies on synchronous uncached disk reads. Asynchronous read-ahead search (
aio_read) has been prototyped, but has not yet been shown to be faster than synchronous uncached disk reads. It is believed that searching is at the physical limits of the disk for standard Macintosh ATA drives.
For single character searches, Hex Fiend uses a custom vectorized search routine that uses SSE2 on Intel and AltiVec on PowerPC. This search routine is significantly faster than
memchr() for in-memory searches.