incrediBILL - 6:06 am on Nov 24, 2012 (gmt 0)

I've always assumed that a formula like ... 12.34.128.0/20 is less resource-greedy than ... %{REMOTE_ADDR} ^12\.34\.1(2[89]|3\d|4[0-3])\.

You are correct.

The DENY syntax is was more efficient than RewriteRule processing just from the perspective of parsing alone. I know it would be had I written it because that's just the way it works. Whether that's the actually reality in execution speed would need to be tested because not all programmers are created equal. :)