RTTFirst of all, we should consider what's the round-trip time.
RTT is the time it takes for a client request to reach the server and get an answer from the server itself. It doesn't include the data transfer time.
The RTT is usually measured in milliseconds.
In order to produce an efficient web page, we should try to reduce RTT and thus reduce the number of HTTP requests and responses.
Already confused? Don't worry, just keep in mind that we have to reduce RTT.
This can lead to a high number of external files. And that's not good for RTT. Infact, loading a lot of files, produces a lot of HTTP requests and responses. This is definitely not a matter of kilobytes: what matters here is the number of times the client is making a request to the server, waiting for the proper reply.
We then should consider the fact that many web gurus are saying the @import rules are to be avoided as well. A nested CSS stylesheets situation is decisively not good in term of RTT.
I've seen charts which explain how the RTT is reduced by one third, using the above method. And that's not bad at all.
If you have specific scripts in the head of the document, remember to put them after the links to external files.
To summarise: put external scripts after external stylesheets; put inline script after all the other resources.
I hope you liked the article. If you want, please share your experience.