For a 100 requests.
$ ruby ~/s/bench_connection_pool.rb
user system total real
without 1.329350 0.059367 1.388717 ( 7.018174)
with 0.222370 0.000000 0.222370 ( 1.659621)
Requests with connection pooling take 76% less time than requests without connection pooling, they also consume less resources.