What’s a hundred milliseconds between friends? Well if you must know it’s an intolerable delay, if your friend happens to be a Search Engine. A hundred milliseconds is a brief amount of time that sits close to the threshold of human reaction time. We can normally react to a stimulus in the 140-200 millisecond range, which is great news for cobras, because it takes a cobra about 100 milliseconds to bite. To put it another way, if a cobra is within striking range and it decides to bite you, it’s too late to stop it. If the mouse pointer moves more than 100 milliseconds after you move the mouse, it feels slow.
So What Does That Have to Do with Search?
Marissa Mayer, Google’s VP of Search Products & User Experience had something interesting to say on this topic at the Web 2.0 conference last year. It began with Google running user tests to try to establish what users wanted. So they asked a group of searchers whether they’d like to see more (than the usual 10) results on a page. When they said “yes” Google upped the number of results to 30. The outcome was that traffic and revenue from this group dropped by 20%.
After wondering why their test group was so ungrateful and scratching their collective heads, the testers suddenly noticed that there was another variable that hadn’t been controlled – the response time. The page with 10 results began to display after 0.4 seconds, while the page with 30 results, needing to collect significantly more data, began to display after 0.9 seconds. And it turned out that it was the response time that was the real “fly in the soup.”
The sad truth is that we humans are so impatient that we’ll not tolerate delays even at the 100 millisecond level. Once response time stretches out beyond our reaction time threshold (140-200 milliseconds) we’re likely to take our business elsewhere. You know how it is:
“Can’t wait all day for a bloody search engine.”
“If this auction takes another 100 milliseconds, I’m gone.”
“Sorry I’d love to read you blog article, I really would, but milliseconds are milliseconds, damn it.”
The evidence suggests Google understood this before anyone else. User impatience is measured in units of 1 tenth of a second starting at 200 milliseconds or so. In her talk, Marissa described how Google saw a substantial boost in traffic on Google Maps when they introduced a new version that rendered faster (because the page size was smaller). The impact was almost immediate.
In a keynote presentation at WSDM 2009, Google Fellow Jeff Dean presented some statistics about Google’s growth in the past decade. He noted that both the number of search queries and the amount of processing power to handle them had risen by a factor of 1000, in that time. Meanwhile, Google’s search latency had gone down from a whole second (1000 milliseconds) to 200 milliseconds. Nowadays, the complete search index to the whole web is held in memory, shared across a thousand machines that divide up the work of handling a query. It’s kinda awesome to think that every time you send Google a query, 1000 computers jump into action.
If you go to Microsoft Search or Yahoo Search to see if there’s any difference, you probably wont detect any – at least I didn’t when I tried it. If anything, Yahoo seemed fractionally slower, but they all gave the impression of being instant. This isn’t a matter of the competitors catching up, so much as all the players realizing that performance is a very important criterion. Google was the first to understand that, just as it was the first to appreciate that search users don’t like cluttered screens with flashing animated adverts.
Do Androids Dream of Electric Apps?
The uptake of Google Apps will increase significantly this year. There are several discouraging factors to the use of web apps and, of course, performance is one of these. The truth is that your word processor-spreadsheet-powerpoint-email apps running on a PC or Mac do not violate your response expectations (unless you try to overload the computer.) To acheve parity, Google Apps have to offer the same level of availability (which they can do by having a client component using Mozilla Prism or Adobe Air) and equivalent response time. That only matters when data transfer occurs, but clearly it cries out for “no discernible latency” over a PC or a Mac when it saves files locally. That’s pretty much the case now.
My expectation is that Microsoft Office will not be brought down by Open Office (although Open Office may deny some revenue to Redmond), but by cloud based Office apps.