Microsoft revealed on Thursday that it has made Hotmail 10x faster since December 2010.

The software giant revealed its claims in a blog posting on Thursday. The company has been working on a number of new ways to speed up its popular webmail service. “We measured how fast our Hotmail pages loaded all over the world,” says Microsoft’s Dick Craddock. Microsoft then compared its results to competitor products.”We were pretty good, but a number of very common actions were just too slow,” admits Craddock.

Microsoft decided to trim a large amount of content from its pages to speed up download times. “Our goal was to make Hotmail feel instant,” says Craddock. Microsoft identified three techniques to improve Hotmail load times.

Caching

The old version of Hotmail used to request data directly from the server each time it was needed. The result was that a number of un-necessary queries were being sent to the backend databases, slowing things down. Microsoft now caches the data after it’s downloaded. Message lists are stored in the browser’s DOM (Document Object Model) so Hotmail can simply call it again without having to re-download it. The cache is cleared each time a user signs out of Hotmail or closers their browser.

Pre-loading

Microsoft analysed their usage patterns of Hotmail and determined that customers generally read the subject lines of new emails when they open up their Hotmail inbox. “We use that time to download and cache the first few messages so they’re ready when you need them,” says Craddock. The approach means the top few emails load almost instantly. “We’re continuing to fine-tune our design to make this as efficient as possible,” says Craddock. “Not all users have this feature turned on by default yet.” Microsoft also preloads code and data in the browser. Hotmail caches the JavaScript and HTML code and address book data that is required for creating a new email. When a Hotmail user creates a new email message or replies, the data is instantly available.

Asynchronous operations

Microsoft’s old version of Hotmail used to have to wait for a server response before displaying and updating the UI. If a Hotmail user deleted a message then they’d have to wait for the server response until they’d see the message list once again. “This made Hotmail feel slow,” admits Craddock. “You felt you had to wait for the operation to complete before you could continue working.” Microsoft’s updated version of Hotmail no longer waits for server operation responses before updating the user interface.

Microsoft finalised the changes a few weeks ago and has been releasing the code to all Hotmail users recently. Open messages, deleting messages and composing messages have all dropped in time by over 90%. The dramatic improvements are demonstrated in a video below. However, Microsoft isn’t finished yet. “We’re not done,” says Craddock. “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.”