No, you're missing the point -- using a regex does not allow you to read in less than all of the input (in the best case, even). If you grep a 1GB file with a r

No, you're missing the point -- using a regex does not allow you to read in less than all of the input (in the best case, even). If you grep a 1GB file with a regex you must read 1GB from disk, no exceptions, and that's many orders of magnitude slower than anything on the CPU (or in memory). With Boyer-Moore you can do less than 100% of the file size in I/O, especially if the given pattern is long relative to the full text.