Say a website on my localhost takes about 3 seconds to do each request. This is fine, and as expected (as it is doing some fancy networking behind the scenes).
However, if i open the same url in tabs (in firefox), then reload them all at the same time, it appears to load each page sequentially rather than all at the same time. What is this all about?
Have tried it on windows server 2008 iis and windows 7 iis
It really depends on the web browser you are using and how tab support in it has been programmed.
It is probably using a single thread to load each tab in turn, which would explain your observation.
Edit:
As others have mentioned, it is also a very real possibility the the webserver running on your localhost is single threaded.