Pagespeed
PageSpeed är ett program utvecklat av Google för att göra internet lite snabbare. (https://developers.google.com/speed/pagespeed/) Om man kollar på källkoden på Googles söksida ser man ett oläsligt hav av tecken, det är resultatet av PageSpeed på deras sida. Det finns moduler för Nginx och Apache. (Pagespeed module is only available as source)
Optimiseringsfilter
Här följer en lista på några användbara filter:
- Local Storage Cache
This filter saves inlined resources to the browser's local storage (an HTML5 feature) on the first view of a page, and loads them from local storage on subsequent views rather than sending them (inline) again.
- Combine CSS
'Combine CSS' seeks to reduce the number of HTTP requests made by a browser during page refresh by replacing multiple distinct CSS files with a single CSS file, containing the contents of all of them. This is particularly important in old browsers, that were limited to two connections per domain. In addition to reduced overhead for HTTP headers and communications warm-up, this approach works better with TCP/IP slow-start, increasing the effective payload bit-rate through the browser's network connection.
- Pre-Resolve DNS
This can contribute significantly towards total page load time. This filter reduces DNS lookup time by providing hints to the browser at the beginning of the HTML, which allows the browser to pre-resolve DNS for resources on the page.
- Collapse Whitespace
The filter reduces the transfer size of HTML files by replacing contiguous whitespace with a single whitespace character. Because HTML is often formatted with extra whitespace for human readability or as an incidental effect of the templates used to generate it, this technique can reduce the number of bytes needed to transmit HTML resources.
- Lazyload Images
The lazyload_images filter defers loading of images until they become visible in the client's viewport or the page's onload event fires. This avoids blocking the download of other critical resources necessary for rendering the above the fold section of the page.
- Insert Google Analytics
The 'Insert Google Analytics' filter adds the basic Google Analytics javascript snippet to each HTML page. If the page already has a Google Analytics snippet inside <head> with the specified ID, then no additional snippet will be added. If another Google Analytics snippet is on the page with a different ID, then an additional snippet will be added with the ID specified in with AnalyticsID. In order to avoid any strange Google Analytics reporting, make sure that the ID specified in the configuration file matches the one used on your site.
- Remove Comments
The remove_comments filter eliminates HTML comments, which are often used to document the code or to comment out experiments. Note that this directive applies only to HTML files. CSS comments are eliminated with the rewrite_css filter, and Javascript comments are eliminated with the rewrite_javascript filter.
Nginx
(Installation)
server {
...
pagespeed on;
pagespeed RewriteLevel CoreFilters;
pagespeed FileCachePath "/var/cache/ngx_pagespeed/";
pagespeed EnableFilters combine_css,remove_comments,collapse_whitespace;
...
}
