Question: Looking into Google Webmaster Tools in the Site Performance section I see that

> 
> On average, pages in your site take 5.0 seconds to load.
> 
> 
> 

Specifically it takes about 5 second to load during last month. However when I personally look pages on my site it rarery takes longer than 1 second to load a page.

How can I discover the reason why Google thinks that pages load slow? Does Google provide any useful info for that? Should I look into web-server logs, etc.? Should I tweak something in robots.txt to prevent indexing some pages or to change crawl speed?

Answer: 
One explanation could be that the average speed is measured all over the world - while you probably measure it from your home computer which is considerably closer to your server than the rest of the world. As an example I can give a website that google says it has a loading speed average of 5 secs, check this out:

![enter image description here](https://i.stack.imgur.com/HmqFH.png)

I recommend on reading [this](http://support.google.com/analytics/bin/answer.py?hl=en&answer=1205784&topic=1282106&ctx=topic) for full understanding of "site speed" section of google analytics
The site speed actually comes from real usage around the world (at least, those with the Google Toolbar installed). See [How exactly is Google Webmaster Tools measuring "Site Performance"?](https://webmasters.stackexchange.com/questions/17137/how-exactly-is-google-webmaster-tools-measuring-site-performance) for more details.

However, from experience I have found that longer-than-expected load times in GWT are the result of a handful of outliers. If you set up Site Speed measuring in Google Analytics, you will see occasional values well in excess of 30 seconds.

Some of these will be users still on slow, dialup connections - 56Kb is around 20 times slower than your typical 1Mb connection. But I believe many stem from connection problems or certain page elements not loading (e.g. a Facebook Like button) or timing out. I doubt anyone would sit for minutes waiting for a page to load, let alone hundreds of people. I have seen load times of up to 330 seconds reported from a single user in Google Analytics. I don't think these can only be slow connections.