Original: According to Google , existing implementations were designed '' for small programs , where the performance and interactivity of the system were n't that important '' , but web applications such as Gmail '' are using the web browser to the fullest when it comes to DOM manipulations and JavaScript '' , and therefore would significantly benefit from a JavaScript engine that could work faster .
Simplified: Existing implementations were designed '' for small programs , where the performance and interactivity of the system were n't that important '' but web applications like Gmail '' are using the web browser to the fullest when it comes to DOM manipulations and Javascript '' .