New 2.3.3 app perf very poor from remote machine

On my development machine (Compaq C700, running a recently updated deployment of Ubuntu 9.04 Desktop), newly created Rails 2.3.3 apps are very slow.

Repro Steps

1. sudo gem install rails --version 2.3.3
   
2. rails foo
   
3. cd foo
   
4. ruby script/generate scaffold Thingy
   
5. rake db:migrate
   
6. ruby script/server

At this point I see the following on the console:

=> Booting WEBrick => Rails 2.3.3 application starting on http://0.0.0.0:3000 => Call with -d to detach => Ctrl-C to shutdown server [2009-08-03 16:49:30] INFO WEBrick 1.3.1 [2009-08-03 16:49:30] INFO ruby 1.8.7 (2008-08-11) [i486-linux] [2009-08-03 16:49:35] INFO WEBrick::HTTPServer#start: pid=11951 port=3000

1. from remote machine (on the same subnet, over a fast WLAN connection) browse to http://MYIP:3000/thingies
   
2. initial page load & subsequent refreshes typically take > 10sec (seconds!) from hitting F5 to seeing the page rendered
   
3. from development machine, browse to http://127.0.0.1:3000/thingies
   
4. initial page load & subsequent refreshes are practically instantaneous

I've attached the development.log from step 7 above; it looks in order but may be of help.

Worth noting is that on the same machines, a newly-created Rails 2.2.2 performs perfectly well. Also, if I take an existing Rails 2.2.2 app and upgrade it to 2.3.3, it experiences the same perf issues, with page views slowing to ~ 10 seconds.

I have also reproduced this on our other dev box, a Mac Pro also running Ubuntu 9.04.

Configuration

OS:
Ubuntu 9.04 (updated as of today 03 July 2009)
Linux duncan-laptop 2.6.28-14-generic #47 scaffold templates include tab characters-Ubuntu SMP Sat Jul 25 00:28:35 UTC 2009 i686 GNU/Linux

Local Gems:
actionmailer (2.3.3, 2.3.2, 2.2.2)
actionpack (2.3.3, 2.3.2, 2.2.2)
activerecord (2.3.3, 2.3.2, 2.2.2)
activeresource (2.3.3, 2.3.2, 2.2.2)
activesupport (2.3.3, 2.3.2, 2.2.2)
aslakhellesoy-webrat (0.3.2.2)
builder (2.1.2)
columnize (0.3.0)
cucumber (0.3.5)
diff-lcs (1.1.2)
gosu (0.7.13.3)
libxml-ruby (1.1.3)
linecache (0.43)
macaddr (1.0.0)
mislav-will_paginate (2.3.8)
nokogiri (1.2.3)
polyglot (0.2.5)
rack (1.0.0)
rails (2.3.3, 2.3.2, 2.2.2)
rake (0.8.7, 0.8.4)
rake-tasks (0.2)
rcov (0.8.1.2.0)
rspec (1.2.6)
rspec-rails (1.2.6)
ruby-debug (0.10.3)
ruby-debug-base (0.10.3)
term-ansicolor (1.0.3)
treetop (1.2.5)
uuid (2.0.1)
webrat (0.4.4)