Every 100ms of latency costs Amazon 1% of profit | Hacker News Reader

Every 100ms of latency costs Amazon 1% of profit

radar.oreilly.com

15 pointsnreece13 comments

Every unsupported claim you read makes you 1% dumber.

Greg Linden used to work at Amazon. From an older blog post of his:

"In A/B tests, we tried delaying the page in increments of 100 milliseconds and found that even very small delays would result in substantial and costly drops in revenue."

http://glinden.blogspot.com/2006/11/marissa-mayer-at-web-20....

Have they tried speeding it up 100ms to see if they gain revenue? I can't believe such a minuscule change has such a huge effect, that's astounding

Disclosure: I used to work at amazon.

I find it immaterial considering the easier thing to speed up is the number of HTTP requests on the site, and that has clearly gotten worse over the years, not better. I pushed heavily to get HTML cleaned up and valid (showing an easy 10-20% reduction with HTML alone), reduce the amount of javascript, etc. It simply wasn't a priority. To be fair, at the time I was there the priority was to grow as fast as possible and deal with profits later.

The power point linked to in the article implies that its from Amazon's own internal data, but unfortunately there's very little substance presented. However, I don't find it surprising that amazon found a high correlation between responsive and overall sales.

It's kind of ironic then how slow Radar is.

Seriously though, site responsiveness is important. If you haven't seen it YSlow is pretty awesome (http://developer.yahoo.com/performance/).

The source slide actually says "+100 ms -1% sales". A 1% drop in sales would likely cost even more in profits, given fixed costs.

In either formulation, it's within the range of plausibility.

In my experience, a single change that makes a web server faster causes a slow, steady increase in traffic over the next few days/weeks, as the audience reacts to the new responsiveness.

Note also that Google considers page load latency in scoring ad relevance, and almost certainly natural search result ranking as well. So everything improves with speed.

If I've decided to purchase something from Amazon.com, I doubt an eye-blink's worth of waiting will change my mind.

You are probably correct, but if you haven't decided then it probably does.

Just to be pedantic an eye blink takes 300 to 400 ms. Amazon's claim is that delays 3 to 4 times less than an eye blink are annoying to people.

Mean reaction time for a human is around 200 ms for a visual stimulus so Amazon is talking about faster than normal reaction time as well.

Frame rate in video games is between 30 and 60 frames per second or one frame every 16 to 33 ms. Cinema is 24 fps or one frame every 40 ms.

So it would appear that Amazon is saying that a delay that a human can perceive is troubling and results in lost sales.

I doubt the dropoff curve is linear. It's probably negligible up to a small threshold (500 ms?) with exponential decay in the tail. I'm willing to believe that a 1-second delay is a 10% hit, though I wonder how that would be measured, but this doesn't necessarily entail that 100ms costs 1%.

Empirical evidence?

"The techniques of web ops are being hoarded by some companies"

Are these techniques patented? Otherwise how does one "hoard" a technique?

Perhaps through the use of trade secrets.

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