As for more specific numbers, this was what I said to someone at the time:
When testing /filter on a a log file with ~137k lines, the average time to finish was 8.8 seconds on v7.1 versus 1.9 seconds on v6.35.
Saving the .log file as UTF16 (instead of the default ANSI/UTF8) shortened this to 5.4 seconds (while doubling the file size).
