Google Sites takes advantage of many SEO techniques and optimization server tools, to help speed up a Sites webpage performance.
Google Sites - Website Speed Optimization include:
Google Analytics now incorporates Load Times from certain browser samples. [retrospectively since june 2011]
To generate a full sample report there now is a
Direct Website Performance statistics will benefit developers and users alike.
For an in dept view of your website and specific speed issues, use the following tools:
Google Code - Website Speed Tools:
This proves the advantage of creating a Mobile Version of your Google Sites.
The Mobile Viewed website is only faster than 40% of mobile websites.
Whereas the Mobile Version website is faster than 70% of mobile websites.