A few months ago I posted about inconsistent performance when running capistrano under Ruby 1.9 when SSH traffic was routed through a gateway host. This problem appears to have been solved in a recent commit to net-ssh-gateway (kudos to Mat Trudel).
I discovered this when installing capistrano 2.6.0. Reading through the updates I saw some promising references to a thread deadlocking issue the existed under Ruby 1.9. After installing the new version of capistrano (and net-ssh-gateway) I re-ran the tests described in my previous post, and sure enough, the improvement is outstanding!
Congratulations and my gratitude are due to the team of people presently maintaining capistrano, net-ssh-gateway, etc.