With 50K newsgroups, the filtering phase goes from ~2000 seconds
to ~90 MILLISECONDS by relying on the grep perlop. This moves
->over checking out of the main dispatch and amortizes the cost
via long_response. (Fairly scheduled) long_response time in
newnews_i now takes ~360 seconds as opposed to ~30 seconds
before this change, however; but the initial filtering speedup
eliminating 2000s is more than worth it.