The last time I evaluated Microsoft's web-based email solution, Hotmail, the company was rolling out a major revision that included, among other things, Exchange ActiveSync support for a first-class mobile experience. Back then, I was looking to see whether I could replace Gmail with Hotmail, but I found that the standard web interface was too slow, compared to Gmail, and contained some UI inefficiencies.

(About 18 months later, I'm still plotting a move off of Gmail, but this will likely involve a migration to Office 365. More on that in the days ahead.)

I was interested to see this week that Microsoft announced a dramatic improvement in the performance of Hotmail when accessed via the web, since this was one of my primary complaints about the service. This change comes in the wake of a similar performance boost (and awesome UI update) to the related SkyDrive service, which I discussed in some detail about ten days ago, and a more minor Hotmail UI update related to keyboard shortcuts.

According to Hotmail group program manager Dick Craddock, the company wants to make the service "feel instant." So performance was improved in a number of ways. These include:

Less content. Microsoft "trimmed content on pages to speed up download time, and eliminated a network round trip on login for further gains." Frankly, if done correctly, this could lead to a less busy design, which would be preferable regardless of any small performance gains.

Caching. Where Hotmail previously requested fresh data from the server every time it was needed, the new version is "more app-like," and it caches downloaded information using features in modern browsers like IE 9. This includes email messages so that subsequent reads are nearly instantaneous. This cache is wiped every time the browser is closed.

Pre-loading. In the new Hotmail version, when users first enter their inbox--and are likely scanning the list of new messages to see whether there's anything important to deal with--the service now downloads and caches the first few messages so they're ready to go.  Likewise, when any email is opened for viewing, the next message is also downloaded and cached; this is because most people who read email will then move on to the next message.

Microsoft also pre-loads JavaScript and HTML code and data in the browser. This way, when you start to compose a new email message, or reply to a message, the cached Compose code and data is swapped in and is ready instantly.

Asynchronous operations. Where the previous Hotmail version would update the UI only when it received a response from the server, the new version no longer waits for server responses (for most operations). The result is a faster feeling and more fluid-feeling UI. So when you do something like delete a message, you no longer have to wait for the server to respond to the delete request; the message just disappears from the UI and you can get on to the next task.

I've not yet tested this new Hotmail version with an eye towards the performance gains, but according to Microsoft, the changes have resulted in dramatic gains. Opening a message went from an average of 3.3 seconds to just .18 seconds, for example. Message deletion? 3.1 seconds down to .14 seconds. And a new message went from 4.3 seconds to just .20 seconds.

There's even a nifty little video showing the two versions performing the same tasks side-by-side.

"We're not done," Craddock concludes. "We believe performance is a feature, and we're committed to making Hotmail as fast as possible. We will continue to find more ways to make Hotmail load faster, and we're also working on ways to improve the efficiency of even more of the most common actions."