Google recently announced on their blog that they are going to rely on page speed as one of the signal for ranking web pages and improving the quality score of the ad. Hence, this is one of the best times to improve the speed of your website and get the benefits instantly.
Here is the video released by Google which would help you to understand more about the importance of site speed.
Tools to optimize your website for page speed :-
https://developers.google.com/speed/pagespeed/
Also See:-
Google Search Quality Updates for August and September
Google Shares Views on Guest Blogging and Links
EMD Update
Page Layout Algorithm
Google Plus and Seo
