I stumbled upon a new tool today that has changed the way I look at on-page optimization. Pingdom released a tool a couple days ago that graphs every file that loads on your page and shows you where your bottlenecks are.
Check it out here:
http://www.pingdom.com/tools/fpt/And since their real service is monitoring uptime, I decided to give them a shot since they're monitoring some of the largest tech sites on the net today. We've been with Alertra for over 2 years but these guys look like they've got a top notch product.
If you've got a mission critical application, I would highly suggest you use a 3rd party monitoring service to alert you to any downtime so you can react immediately.
Here's a before and after of what d.i.c looked like with and without keepalive on in apache (left: before, right: after):
