Yesterday New York Times published a great post by Richard Macmanus at
ReadWriteWeb:
Tumblr Leaves Posterous in the Dust. Tumblr and Posterous are both “light blogging service” providers. Both services have great value propositions: making it easy for anyone to publish things very quickly and at the click of a button. As head to head competitors, both startups have been getting a lot of attention and look like they are achieving similar levels of success on the surface. However, Richard pointed out that Tumblr has out-grown Posterous significantly over the last year(see the
Compete.com chart below):

I highly recommend people taking a look at Richard’s post as it reveals interesting data points and presents a good analysis on how the two are doing. As far as the “The Keys to Tumblr’s Success”, Richard attributed it to Tumblr’s first mover advantage.

First mover advantage? Maybe. A close examination using
Yottaa Insight quickly reveals another reason:
web performance. According to the Internet Performance Archive data that Yottaa Insight collects everyday,
Tumblr has been twice as fast as Posterous.

Page Load Time Comparison

The following table shows the page load time for both Tumblr and Posterous,  averaged from data points measured from different geographic locations over a few months:

Average load time comparison
	Tumblr	Posterous
Time to Display: The amount of time from when a URL is entered into a browser to when the page is mostly rendered but not ready for user interaction yet	2990(ms)	6034(ms)
Time to Interact: The amount of time from when a URL is entered into a browser to when the page is loaded, rendered and ready for usage.	3588(ms)	7222(ms)

(Data source: Tumblr Page Load Time on Yottaa Insight and Posterous Page Load Time on Yottaa Insight)

Historical Performance Trend

Looking at histroical performance trend, Tumblr has been consistently outperforming Posterous by a large amount. The following chart shows the historical performance trend for Tumblr and Posterous over the last 30-days (
click the chart to enlarge it):



(data source: Tumblr and Posterous Performance Benchmark, select “page load->Time to Interact” from the chart)

Interestingly, Tumblr had some issues on August 23rd as you can see a big change on that day (If you dig a little bit more, the issue only happened to users in San Francisco Bay area. Users in other geographies were not efffected. See
/url/4c6154324d7cd54aad00010d/page_load. Likewise, you can also see Posterous had some issues in early September).

Web Performance As Key Factor To Tumblr Success
 

Among all possible reasons, Web performance is most likely one of the key factors that Tumblr has been outgrowing Posterous signficantly. Of course, it is still early to say that Tumblr is winning the light blogging service battle. There are many things Posterous did well. Improving its performance to match Tumblr’s can definitely make a big difference.

Note: from Tumblr and Posterous Performance Benchmark, you can drill into it to understand which factors contributed to the “slowness” for Posterous. For example, if you compare global reachability, Tumblr and Posterous are fairly comparable in terms of DNS time, Connection Time, but Tumblr is significantly better in First Byte Time and Last Byte Time.

Methodology
 

All data points in this article are from Yottaa Insight, an open service for analyzing and monitoring web performance. Yottaa Insight provides on-demand assessment, real-time monitoring and serves as an an open Internet performance archive, where you can benchmark and compare the performance of web sites. Unfortunately, this service wasn’t in operation until a few months ago so the data shown in this article are only data points collected over the last few months.

Some relevant links are (these are live links that you should drill into specific metrics such as page load, reachability, etc to get into details): Tumblr Performance Profile, Posterous Performance Profile, Benchmark Comparison between Tumblr and Posterous.
 

Closing Note:Website Speed is The Most Important Feature

I’d like to quote Fred Wilson as the closing note here. Fred is an investor of Tumblr and they clearly understand the importance of web performance. As he pointed out in this blog, Fred said:

First and foremost, we believe that speed is more than a feature.
Speed is the most important feature. If your application is slow, people won?t use it….If something is slow, they?re just gone.

We think that the application has to be fast, and if it?s not, you can see what happens…When we see some of our portfolio company?s applications getting bogged down, we also note that they don?t grow as quickly. There is real empirical evidence that substantiates the fact that speed is more than a feature. It?s a requirement.

Yes, you heard it. Performance is #1. As the growth pattern of two highly interesting startups has shown, web performance makes a really big difference in business success.