Simple guidelines to optimize online resources

Now every other site offers its own set of tips to increase the performance of sites, they have a search engine Yahoo.

Firstly, when using HTTP do not forget:
- Avoid HTTP requests - less than them, so much the better;
- Use the headings «Cache-control» or «Expires»;
- Forget about redirect (HTTP Redirect).

Second, Java scripts require care:
- When writing a document at the beginning be sure to specify links to files with style sheets (link href) .a end prescribe a link to a file JavaScript (script src);
- Insertion of CSS and JavaScript files are stored separately;
- When using CSS, and JavaScript reduces the file size with the utility YUI compressor or JSMin. They allow to deal with unnecessary comments and extra spaces, as well as reduce the variables.
- Check the script files to duplicate code that makes reloaded rates and delay the update of the page;
- Get rid of Java requests to the DOM, at least partially, by doing caching, casts repeated requests;
- All blocks Java with images leave the load in the least;
- When handling events in a pinch, use onresize, audits were carried out using YUI Event, and the usual "onload" to replace utility DOMContentLoaded.

Third, when dealing with Ajax requests:
- Cache them;
- Use GET, accommodating all requests in a single packet TCP.

Fourthly, CSS is also possible to optimize:
- Do not litter CSS computable expressions (expression);
- Be sure to reset the buffer still at the start page was generated by periodic call flush () in PHP, then the user will download CSS files;
- To load the CSS, use at the beginning of the page is notimport, and "link";
- Forget about the filters, they are supported only IE / better take into circulation PNG8.

Fifth, be patient and careful when writing the site:
- All pages before giving compress, for example, through the utility mod_gzip;
- To use the services of content delivery networks such as Akamai;
- In page does not prescribe more than three links to other domains, whether referring to a picture or iframe, because the site has to wait for an answer other people's servers;
- When using IFRAME, try to keep only the basic, as well as get rid of references to other people's resources, or the page may remain locked;
- In Apache configure ETags;
- Rationally selects those scripts that are needed in the initial charge;
- And all the content divide in equal shares by the existing domains, then the browser to load all the data at the same time;
- Minimize the number of elements in the tree DOM, remove unnecessary tags;
- Trite, but make sure that you do not appear error 404;
- Cut the size of Cookie: abbreviate names, define the length of life, remove all unnecessary;
- In support pages instead use Cookie imposition of scripts static.domain.com;
- If you choose to add Flash, pre-define the crossdomain.xml.

Sixth, pay attention to the image:
- Work on the used image (used to reduce the size palette, fill the image * PNG format using a utility optipng, pngoptimizer or pngcrush, delete comments, and in the case of * jpg optimize files via jpegtran);
- To create the background images using CSS sprites;
- Check the coincidence of the real size of the image with prescribed parameters width and height (there will be no problems with scaling).
- Remember that the favicon.ico should not exceed 1 KB and to be cached, because search engines use it in every tenth request.

And finally, in the seventh, when creating a site that is optimized for mobile devices:
- Do not create multiple pages, more than 25 KB;
- Use multipart blocks that allows automatic packaging of all additions to the application.