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February 11, 2009

Google Search Pages Load Faster if You Use Google Toolbar

Google Toolbar for Internet Explorer implemented Shared Dictionary Compression over HTTP (SDCH), a technique that speeds up loading web pages. According to Google's proposal (PDF), SDCH is "an HTTP/1.1-compatible extension that supports inter-response data compression by means of a reference dictionary shared between user agent and server".

The proposal explains that "retrieving a set of HTML pages with the same header, footer, inlined JavaScript and CSS requires the retransmission of the same data multiple times. [SDCH is] a compression technique that leverages this crosspayload redundancy."

One of the sites that benefit from this extension is and Google decided to add support for SDCH in Google Toolbar for Internet Explorer.

A Google help page provides a way to remove the feature by disabling the "Google Dictionary Compression sdch" add-on, corresponding to the file fastsearch.dll from Google Toolbar's main directory. There's even an example when the dictionary compression doesn't work well.

The developer versions of Google Chrome implement SDCH as well. Here's an example of dictionary for


  1. Well it makes sense, should save Google bandwidth too, after all both ends have to pay.

  2. One reason I got rid of Google Toolbar was it seemed to slow my system down (very slightly though and these things can be very subjective). The Linux version (that I'd be using) seems to always be running behind in features and I got tired of being a second class citizen.

    Enter Chrome. For some people. I look forward to trying it when available. Funny, I don't know any Windows users who have switched to Chrome, and most of them have never heard about it. I agree with Sergy Brin that the fact that they don't have a Linux (or OS X) version is an embarrassment. I hope they get un-embarrassed soon.

  3. I have (probably the newest version of) Google toolbar on Firefox 3.0.6/Win 2000 and while my upload speed is high, because Im sending a file or something else causes it, I get error pages a lot more often, which say, that the page could not be found. After I refresh, the page loads. I tried the same scenario with less available upload without Google toolbar and I get less error pages saying that page could not be found and I should contact my ISP, mostly on pages with possibly very high traffic.