Google Webmaster site performance - apparently website loads slow

Question

I have a website which was hosted in Germany till last month. Then this month I moved it to a US based server. The new host is one of the best and top ranking dedicated hosting provider. Ever since I have moved the site, I have heard people saying site loads slow now. Although I personally haven't seen it because when I open it myself or use some 3rd party website speed checker then it shows excellent speed. But the thing is when I go to Google Webmaster and there is a something called "site performance" under "Labs" then it shows that my site's loading time is increasing. And the home page is taking on average 10 seconds to open completely. But of course when I open website myself or if I ask my friend, we don't notice such delay. In fact this is totally absurd that Google is saying 10 seconds for home page! Upon reading further about site performance I came to know that this is the data that Google collects from Google Toolbar that users have installed. So that means its results could be skewed and totally unreliable!? But two people I talked to said that its not just toolbar but Google also collects this data by other means. Although Google help documents only mention about toolbar. So I want to know what is true? And when you see crawl stats then Google says that it took an average 0.6 seconds to crawl one page. So crawl stats is showing something else while site performance is showing totally different.

Secondly what tools and techniques can I use to really see what the problem is? Shall I look into webalizer or raw access logs? I have also looked into MySQL logs and found some queries which are slowing site performance but not on home page. And that too has only happened twice for a brief period of 1 or 2 minutes when site was not loading at all due to MySQL server being busy. What data shall I look for in logs and stats? If there really is some problem then I want to go to bottom of it.

Thanks

Answer 1

A slow database query can cause a lot of problems. If a slow query locks a table, it's locked until the query's done. Or if it has to write a huge amount of data to a temp file due to bad indexing, it can affect anything that touches the drive it's writing on.

Step one to improving server performance (without getting into code profiling & hardware tweaking): caching. MySQL has an internal query cache that can be tuned relatively easily, and there are a lot of ways to set up a page cache, depending on what tools you're using. Nothing's faster than serving static HTML files.

And it might be obvious, but geography does matter. If your users are in Germany, moving your server across the Atlantic added some latency. Swimming across the ocean twice takes time, even at the speed of light, and satellites aren't as reliable as the submarine cables. If your users are now farther away from your server, your site did just get slower, and possibly enough to notice and complain about.