vb.org Archive - View Single Post - How Design Affects Performance : Progressive Rendering

Princeton · #5 10-28-2007, 06:12 PM

a browser will download all the objects within the <head> before any objects within the <body> of a document...

a large javascript file (or multiple) will cause a delay in rendering the page (non-cached)

by placing the JavaScript files at the bottom of the page you are telling the browser to download all the objects on the page prior to downloading the JavaScript files (by placing the files at the bottom the end-user will not be affected by the delay in downloading the files)

the point here is to know the difference and to choose one or the other ..
you do not want to place JavaScript files in the middle of the <body> as it will slow the rendering of the page as the browser will have to
1)__ Stop,
2)__ Download the javascript file,
3)__ Parse/interpret javascript file,
4)__ Continue to next object

as you can imagine by placing a large javascript in the middle of the page will cause a visible delay

X vBulletin 3.8.12 by vBS Debug Information
Page Generation 0.01063 seconds Memory Usage 1,760KB Queries Executed 11 (?)
More Information
Template Usage: (1)SHOWTHREAD_SHOWPOST (1)ad_footer_end (1)ad_footer_start (1)ad_header_end (1)ad_header_logo (1)ad_navbar_below (1)footer (1)gobutton (1)header (1)headinclude (6)option (1)post_thanks_box (1)post_thanks_button (1)post_thanks_javascript (1)post_thanks_navbar_search (1)post_thanks_postbit_info (1)postbit (1)postbit_onlinestatus (1)postbit_wrapper (1)spacer_close (1)spacer_open Phrase Groups Available: global postbit reputationlevel showthread	Included Files: ./showpost.php ./global.php ./includes/init.php ./includes/class_core.php ./includes/config.php ./includes/functions.php ./includes/class_hook.php ./includes/modsystem_functions.php ./includes/functions_bigthree.php ./includes/class_postbit.php ./includes/class_bbcode.php ./includes/functions_reputation.php ./includes/functions_post_thanks.php Hooks Called: init_startup init_startup_session_setup_start init_startup_session_setup_complete cache_permissions fetch_postinfo_query fetch_postinfo fetch_threadinfo_query fetch_threadinfo fetch_foruminfo style_fetch cache_templates global_start parse_templates global_setup_complete showpost_start bbcode_fetch_tags bbcode_create postbit_factory showpost_post postbit_display_start post_thanks_function_post_thanks_off_start post_thanks_function_post_thanks_off_end post_thanks_function_fetch_thanks_start post_thanks_function_fetch_thanks_end post_thanks_function_thanked_already_start post_thanks_function_thanked_already_end fetch_musername postbit_imicons bbcode_parse_start bbcode_parse_complete_precache bbcode_parse_complete postbit_display_complete post_thanks_function_can_thank_this_post_start showpost_complete
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