Excellent post on the importance of web page performance:
Performance isn’t a technical niggle that “we should get around to fixing”. It is an opportunity to grow your audience, to grow your business, to convert more sales (or whatever it is eCommerce people do).
Performance is an opportunity, and a risk, the same way that a redesigned template is. Or a new logo. Or a change to the colour of a button CTA.
See also: Tim Kadlec’s 2012 post on 24 Ways.