The prefetch functionality in firefox is a security loophole.
Firstly it's a completely unwanted function. I don't care if my website loads a second faster than it usually would. Secondly it can get your machine to download malware from websites you have not even visited.
For instance, I was doing some Google SERP analysis for one of my clients who sells adult products and what do I see? Malware being downloaded from a website I did not even visit.
I did shut down the function later on, but this is a nuisance. This is definitely not bright coming from a browser that claims to be super secure.
Hope chrome does not have this feature.
[edited by: tedster at 5:27 pm (utc) on Jan. 23, 2010] [edit reason] moved from another location [/edit]
I doubt they use the results from any browser toolbar for their official numbers. Its far more likely that they measure the page speed when googlebot spiders visit the page.
I've seen references that they do use the Google toolbar data to get real world numbers for page loading. I'm sure they also use googlebot times as well. HOWEVER, googlebot only measures the download time for the HTML file itself; googlebot can not measure how long it takes pages to load for real users. Only the toolbar can measure real world page loading and that toolbar is heavily skewed towards MSIE.
I seriously doubt that even if we allowed Firefox to prefetch pages this would have any measurable impact on Google's page speed numbers because I do not believe that Firefox prefetches all links on a page (which would be traumatic for the website in question). Instead it may prefetch based on prefetch suggestions provided on webpages. This means that the odds that the user actually clicks on a link for a prefetched page is probably really low.
The only way I see prefetch being of any value to anyone involved is if users have a high probability of going from page 'A' to page 'B' and there is a prefetch instruction for the link to page 'B', but not other links on page 'A'. Beyond this, prefetch is a total waste of bandwidth and server resources.
Users should be able to easily disable it from their browser options panel if they don't want to use it. HOWEVER, the way it is implemented in Firefox, it can only be disabled if one knows the "secret" configuration setting. This is not right. There can be many different and very valid reasons why someone would not want their browser prefetching links. As such the fact that the settings for this feature are hidden from the average user is wrong.
[edited by: tedster at 6:20 pm (utc) on Jan. 30, 2010]