Archive for June, 2009

I just got back from Velocity, a new-ish (2nd one) performance & scalability/availability conference. Last year, a common complaint was a lack of presentations around “why speed matters” and this year they did not disappoint.

First, Google and Microsoft teamed up to present the results from experiments on the impact of performance on their search business:

The Bing graph shows that just a 1/2 sec. delay before sending the search results had a -1.2% negative impact on revenue. A 2 second delay had a -2.1% impact.

Google slowed down their load progressively, and found that delaying 400ms after their header (logo, etc.) resulted in -0.59% less daily searches per users.

The next day, Marissa Meyer (VP, Google User Experience) gave a talk and revealed their historic findings:

They delayed results 400ms and searches/user decreased -0.44%, then to -0.76% after six weeks. After removing the delay, users did -0.21% fewer searches, hinting at an after-effect to speed. She noted this was “millions” in potential revenue that could be lost.

Shopzilla.com (shopping comparison search) made an optimization (much like we have done at AOL) to move their static images off the “*.shoppzilla.com” domain to avoid cookie pollution from the top level domain.
This tweak earned them a 0.5% top line revenue increase.

They went on to improve their performance from 4-6 seconds to 1.5 seconds, and had the following results to share:

Conversion rates increased 7 to 12%. Page views increased 25%. They found Google rewarded them in search results for SEM (speed is an SEM quality factor) 8% increase in SEM visits in the U.S., and 120% in the U.K.

Dave Artz (yours truly) gave a talk on AOL’s secret weapons in optimization, and shared some new research he’s done with their internal tracking system’s data.

We took a sample of visits over the course of a day on various AOL sites, and calculated the average load time of the pages on each visit. We then broke the visits into percentile groups, the top 10th percentile being the fastest 10% of visits and the bottom 100th being the slowest 10%, and examined the Page Views within each visit group (fyi, refreshing photo galleries were not counted as page views):

The data showed that the visits with the fastest load times delivered the most page views, and degraded (sometimes quickly) as load times decreased. We found a clear correlation between faster/slower visits and page views.

Now you may be wondering, how do I get faster? IM me, we’ll talk about it.