This entry on MSDN (Microsoft Developer Network) is a good piece on the basics of web performance engineering. While reviewing the steps covered in the article I discovered that one of my Apache servers had KeepAlives disabled, it appears that the default value for this has changed from ‘On’ to ‘Off’. The performance improvement was immediate and obvious.
It discusses several basic concepts including TCP settings, web server options and to a lesser degree client side methods for improving web page load times. It also explains the use of a free tool available from Microsoft (imagine that – something free from Microsoft!); Visual Round Trip Analyzer. I am downloading it as I type this.
It’s amazing how quickly time passes when you take a few business trips and hunker down to churn out a few software releases. I pulled my nose off the grindstone the other day to discover that someone had replaced my lawn with about a foot of oak leaves – not cool!
I managed to upload a few new photo sets to Flickr. Seattle’s famous Public Market (where they throw the fish around); La Jolla, CA and a visit to the Stone Zoo in Stoneham, MA. The picture you see to the left is from that set. I have a thing for big cats. 😉
Contains custom information set by the web developer via the _setCustomVar method in Google Analytics. This cookie is updated every time new data is sent to the Google Analytics server.
2 years after last activity
__utmx
Used to determine whether a user is included in an A / B or Multivariate test.
18 months
_ga
ID used to identify users
2 years
_gali
Used by Google Analytics to determine which links on a page are being clicked
30 seconds
_ga_
ID used to identify users
2 years
_gid
ID used to identify users for 24 hours after last activity
24 hours
_gat
Used to monitor number of Google Analytics server requests when using Google Tag Manager
1 minute
_gac_
Contains information related to marketing campaigns of the user. These are shared with Google AdWords / Google Ads when the Google Ads and Google Analytics accounts are linked together.
90 days
__utma
ID used to identify users and sessions
2 years after last activity
__utmt
Used to monitor number of Google Analytics server requests
10 minutes
__utmb
Used to distinguish new sessions and visits. This cookie is set when the GA.js javascript library is loaded and there is no existing __utmb cookie. The cookie is updated every time data is sent to the Google Analytics server.
30 minutes after last activity
__utmc
Used only with old Urchin versions of Google Analytics and not with GA.js. Was used to distinguish between new sessions and visits at the end of a session.
End of session (browser)
__utmz
Contains information about the traffic source or campaign that directed user to the website. The cookie is set when the GA.js javascript is loaded and updated when data is sent to the Google Anaytics server