Recommended website performance monitoring services? [closed]

I'm looking for a good performance monitoring service for websites. I know about some of the available general monitoring services that check for uptime and notify you about unavailable services. But I'm specifically looking for a service with an emphasis on performance.

I.e., I would like to see reports with detailed performance statistics from multiple locations world-wide, with a break-down on how long it took to fetch the different website resources, including third-party scripts such as Google Analytics and so on (the report should contain similar details such as the FireBug Net tab). Are there any such services and if so, which one is the best?

Check out the answer to a similar question which should help: Can anyone recommend a website monitoring service?

To answer your question more specifically however, every major monitoring service will provide performance metrics in addition to basic uptime/availability notifications. For example, the Top Tier (Webmetrics, Keynote, Gomez) will give you waterfall graphs that show you a timeline showing how every item on your page loads from all around the world.

The most important thing to look for when you look for a vendor in this area is the monitoring technology. You want to make sure that the monitoring happens with a real browser, not an emulated browser. You want to see the performance based on how real users will be seeing your site, including the maximum number of simultaneous threads, how javascript and css are handled, and the general performance that a real browser gives you. A few of the vendors have been known to claim they are monitoring with a real browser, when in reality they aren't, or it's a lot more expensive.

To determine which is the best, I would recommend you get a trial with each one and see for yourself.

Note that this kind of information, especially if you are looking for performance from locations around the world, is what separates the top tier from the bottom.

I guess what you need is transaction performance monitoring? In other words, not just page load times but the performance of a series of steps (transactions) on your website?

If so, I can recommend AlertFox. It is by a wide margin the best transaction monitoring tool and very cost effective. They also have free plans so you can test for yourself.

Pingdom seems like a good fit for your needs.

Edit: In case it isn't evident, you can monitor perfomance, not only uptime. You do this by defining what resources will be checked, and then you'll get a report with the results from different locations.