[Princeton]

In other words, this Google Labs feature is not very useful at all on sites with global traffic.

it doesn't matter where your visitors are coming from - a high # is an indicator that your site needs tweaking

it's a useful tool but don't rely on it - use it as an indicator of how well your changes are working

this tool averages the amount of time that the entire page takes to load to the end-user ... this includes html, images, scripts, javascript execution, css, etc ... your server may output the html in 0.9sec but by the time the page loads completely to the end-user that 0.9sec may turn into 12 sec

unlike Googlebots this tool parses all pages - this includes pages that are disallowed via robot.tx and other pages that are not normally indexed by Googlebots

for example, reply.php, newrepley.php, etc, etc are pages that are not normally accessed by Googlebots

however, the toolbar will count these pages in your overall site performance
(because of the javascript involved in displaying the wysiwyg editor these pages render slow which will increase your site performance average)

another thing that may affect how fast your page load is your page design - to learn more about this read a few of my articles (found in sig)

if you are currently getting a high number - it means you need to work on your pages...
Google has already stated that it may use web page speed for indexing pages.