Google has started rolling out an upgrade to its Gmail service to better support planned upgrades.

A spokesperson told vnunet.com that the company is in the process of updating Gmail's JavaScript coding to make the service "faster and more flexible".

The changes will be applied to the US English version of the service to begin with, followed by international versions a few weeks later.

Gmail engineer Dan Pupius explained in a company blog that the update will allow the service to handle features that had not been anticipated when Gmail launched in 2004.

"In the past three and a half years we have launched a number of cool features," wrote Pupius.

"During this time we have learned a lot about building large web applications and what happens when you push web browsers to their limits."

Pupius explained that the update includes elements from other services, such as the rich-text editor used by Google's Page Creator and Groups services.

Google engineers have also added keyboard shortcuts and the ability to bookmark messages or email searches.

Much of the work on Gmail is aimed at improving the speed of the service. Pupius pointed out that a loading delay of only a few seconds for each message can mean hours of wasted time when users wade through their email.

"We have spent a lot of time profiling all parts of the application, shaving milliseconds off wherever we can, and figuring out workarounds for some pretty deep-rooted issues with the current browser implementations," he said.

However, the update will also bring some unwanted side-effects for users running third-party extensions such as file managers and notification tools.

Pupius said that Google will be working with developers to update the add-ons, but admitted that many are "likely to stop working" the after the update.