Faster downloading of webpages .

Calling external webpage components from a seperate domain

[getxb]

Is it true that if a reasonably big site (example.com) moves all its JS/CSS files and Calls them from an external domain altogether (like js.example1.com css.example1.com OR example2.com), the site will be comparatively much faster. If so why?

Will that be any issue from SEO perspective?

Regards,
Ramnath

[lammert]

Browsers currently load only two items at the same time from one domain. If you put site furniture on another domainname, browsers start an extra two downloads for every different domainname. The maximum number of supported parallel transfers is eight in most browsers.

There is however a downside. Every domain needs a domainname lookup before the transfer can start. This adds extra overhead. There is also an inherent problem in most current browsers that they are not able to load JavaScript files in parallel. This is by design to prevent early execution of small javascript files which are completely loaded before a larger script file that appears earlier in an HTML source.

I don't know much about SEO problems, but I haven't heard of large negative effects.

[getxb]

Thanks a lot for your response.