blog post | FAQ

Hammerhead adds a tab to Firebug for measuring the load time of web pages.

To install:

  1. install Firebug
  2. install Hammerhead

In Firefox 3, if you get this error:

"Hammerhead" will not be installed because it does not provide secure updates.

follow these steps:

  1. enter "about:config" into address bar
  2. right click somewhere in the list of keys below; select New->Boolean
  3. enter "extensions.checkUpdateSecurity" as the name
  4. select false as the value
  5. install Hammerhead again

Hammerhead Features

Load Time

Hammerhead adds an icon to the Firefox statusbar. Next to the icon is shown the current page's load time.

Clear Cache

Right-clicking on the icon displays a menu from which you can quickly clear both caches (disk & memory), or just the memory cache.

Permanently Clear Cache

When Hammerhead is opened, the Cache & Time panel shows the page URL and load time. You can clear the cache once by clicking on the desired button. What if you're testing a change and want to load every page with a cleared cache? Choosing one of the radio buttons, "Clear disk and memory caches" or "Clear memory cache only", will clear the appropriate cache before every page load, making it easier to always test for the empty cache or primed cache user experience.

Measure Multiple Pages

The Hammer panel lets you specify multiple URLs that you want to measure, and how many measurements to gather ("# of loads"). Each URL is loaded the specified number of times for both the empty cache and primed cache scenario. The number of measurements, mean, and median is displayed, along with the most recent load time. Open the Setup panel to change the defaults, for example, to only test empty cache. You can export the data, too.