[CLK-284] Update PageImport to increase page rendering performance

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: core
• Environment: 1.4 RC2
• Assignee: Malcolm Edgar
• Reporter: Malcolm Edgar
• Created: 10/Jan/08 05:55
• Updated: 11/Feb/08 03:48
• Resolved: 31/Jan/08 07:16

Description

The book "High Performance Web Sites" by Steve Sounders identifies a number of issues which degrade web page rendering.

#1 If a JavaScript imports listed above CSS imports will delay the download of the CSS imports until the JS imports have completed.

#2 JavaScript blocks <script> </script> in the header of the page will delay the progressive rendering of HTML until the entire page has been downloaded.

The Click PageImports class could be modified to support $headerImports which include an ordered list of import statements, with JS imports following CSS imports. The class could also provide a $footerImports which contains JS blocks to be included at the bottom of the page.

To support backward compatability the $imports should still be maintained, but should have CSS imports listed above JS imports, with JS script blocks following last.