Overview
You can speed up your loading times on unencrypted pages of your Magento store by utilising parallel connections. Most browsers are limited to making only a small number of connections to a domain in parallel; by fooling the browser into thinking it’s loading objects from several domains on one page it will increase the number of concurrent connections to the server.
Note: this only works on unencrypted pages. For pages on your store which use SSL encryption this would be counterproductive, as it would produce unauthenticated content.
Please note there are 2 additional requirements: we assume that your domain’s nameservers are with us so that DNS records for the additional sub-domains you create will propagate out naturally. Otherwise you will have to create these records with your DNS provider.
In additional, we assume that you are not using the Fooman Speedster extension, because it doesn’t seem to honour Magento base URLs (please be aware that the Fooman Speedster has issues if you try to disable it).
(As ever Nublue recommends that you backup your Magento store using your Plesk Panel’s Backup Manager tool before undertaking any configuration changes on Magento. Please see here for a guide on backing up your website.
Method
1) Login to your Plesk Control Panel
2) Navigate to your Magento domain
3) Click on Domain Aliases
4) Add the following 3 domains (replacing domain_name.com with your domain):
css.domain_name.com
js.domain_name.com
media.domain_name.com5) Test the aliases are working by navigating in a browser to the domain aliases you’ve created. You will either see your store on that URL or it will forward to the URL of your store. So long as you see your store in the end, it’s working!
6) Now login to your Magento Admin Panel
7) Navigate to System > Configuration
7a) For Magento multistore configurations only: choose your configuration scope using the dropdown.
8) Choose the Web option on the left navigation bar
9) Ensure you are only looking at Unsecure Base URLs
10) Change the following entries, replacing your_domain.com with your domain, and ensuring you replicate all trailing forward slashes:
Base Skin URL Use: http://css.your_domain.com/skin/
Base Media URL Use: http://media.your_domain.com/media/
Base JavaScript URL Use: http://js.your_domain.com/js/
DO NOT make any changes to Base URL and Base Link URL.
10) For Magento multistore configurations only: untick ‘Use Default’
11) Save your configuration changes.
12) Refresh your Magento cache (either using our ‘Control Panel’ option or using the Magento Admin panel ‘Cache refresh’ option.
You can test using the Firefox extension Firebug. Open up the Net tab and load your site’s pages to see the parallel connections in action.
Please note: not all web-based page load speed tests replicate browser behaviour, so it’s quite possible (and quite probable) that they will show no change across the two sites.
Reversing the change
Should you wish to reverse the changes you’ve made, you simply need to update your Magento store’s base URL settings to how they were before, then refresh the Magento cache again afterwards.