The new New Tab page in Firefox 13 finally brings a Speed Dial-style, frequently visited sites thumbnails to a blank tab. (Credit: Mozilla)

A number of improvements that Mozilla has built into today's new Firefox release find the browser playing catch-up, treading water, and forging ahead all at the same time.

If it sounds like a near-impossible juggling act to you, you're not alone.

Firefox 13 (download for Windows | Mac | Linux) comes with feature changes and tweaks under the hood. The new features include a redesigned New Tab page that shows you thumbnails of your frequently-visited sites, often dubbed Speed Dial in honor of Opera's take on the feature. Firefox is the last of the major browsers to get some variation of the feature.

Whereas the previous home page showed only a Google search bar and two small text links at the bottom of the screen, the new one includes large icons to give you easy access to downloads, bookmarks, history, add-ons, sync, and settings. You can access the home page at about:home.

Those changes are good but quite minor. One move that will help Firefox immediately move ahead: its support for Google's SPDY protocol is now on by default. SPDY affects browsing in two ways, assuming you're loading a Web page that support it. It's a more secure successor to HTTP because it forces SSL encryption for all sites, and it's a faster protocol, too.

The new home page in Firefox 13. (Credit: Mozilla)

There's a number of reasons for that. Three of the major ones are that it can request multiple site elements over a single connection; it can assign priorities to those elements so more important ones show up first; and it can compress header data. So, if you're loading a site in Firefox that supports SPDY, it ought to finish loading much faster than otherwise. Two notable sites that support SPDY are and

Currently, only Chrome and Firefox work with SPDY.

On the performance backend, Firefox 13 makes a few adjustments that ought to result in a more pleasant browsing experience for most people. If you have multiple tabs load when Firefox starts, the browser will now only load the the Web page content of the active tab. This means that for heavy tab-abusers like myself, we'll be able to get started in the browser much faster.

The new version of the browser also does a better job at memory management and has shrunk its start-up time.

Developers tools also see a large batch of small improvements in Firefox 13, such as making recently opened but now closed panels reopen simultaneously so that tools re-appear en masse; and saving CSS files loaded locally without a save prompt for a faster workflow.