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How can I translate what all this means?
09-07-2010, 10:42 AM (This post was last modified: 09-07-2010 10:46 AM by danacton.)
Post: #8
RE: How can I translate what all this means?
(08-29-2010 08:56 AM)pmeenan Wrote:  
(08-28-2010 11:45 AM)danacton Wrote:  Pat,

Thanks for the quick and useful response. That is, all of it my lame brain could absorb. I'm somewhat reluctant to merge the CSS and JS files, since this is a DNN Portal, but I will consider all I can to merge and cut them out completely. I don't know if you're a DNN guy, but maybe you could answer this question for me?

1. What the heck are all the .js files doing there? This (like you said) and the .CSS files must be slowing things down. Guess I should be asking the guys at PowerDNN right?

2. I just read a bit about js compression and how it zips your js files. I will ask them to enable it in IIS and I will ask them why there are so many js files? Do you have any idea?

Sorry, until you had mentioned it I had never heard of DNN but looking now it looks like a CMS platform much like Drupal, Wordpress or Joomla (though thouse are php and DNN is .Net). PowerDNN isn't going to be able to help unless they set up your actual site. The different js files are usually pulled in by the themes and plugins.

Usually the merging has to be done either by the CMS itself or by a plugin for it. Found this which might help:

(08-28-2010 11:45 AM)danacton Wrote:  3. I'm not sure what you mean by using image sprites. I always thought if the image was tiny in size that was a good thing, but after seeing all of thes requests, I'm thinking this is way too many requests? What's a sprite and can I change .png, .gif, .jpg files to support sprites?

A sprite is a technique that goes back to the early video games. What you do is you take all of your small images and you put them together into a single larger image and then when you need the image you pull out just the part of the larger image you are going to use. The combined file is usually a bit smaller than the individual files but the really big win is that you can get it all in a single request.

You can usually only use it for css background images (most of your gif's and png's) which are used for things like buttons and borders.

SpriteMe is a tool that Steve Souders write that will do most of the work for you automatically on your page: I'm sure there are others as well.

(08-28-2010 11:45 AM)danacton Wrote:  4. Finally, what does "CDN to reduce the latency for the remaining requests" mean? I'm not sure what latency is, and not sure how a CDN can be helpful - can you elaborate on that?

Sorry, the latency is the time that each individual request takes to get from the user's browser to your servers. It looks like it was ~150ms from the Dulles test location. As you move further away from the servers that time increases (largely limited by the speed of light through fiber). From somewhere like New Zealand those individual requests could take as long as 500ms which when added up will make your whole page load 3-4 times slower.

A Content Delivery Network (CDN) is a service that has servers in different parts of the world and they make copies of your static content (images, javascript, css) and the users browsers request the content from the closest server instead of coming all the way back to yours.

It is more important to first reduce the number of requests but after you have them as reduced as you're likely going to be able to get you should see if it makes sense to use a CDN.

If all of your customers are geographically close then it doesn't make sense but if you have a global customer base it can be critical.

(08-28-2010 11:45 AM)danacton Wrote:  5. Question: If I have CSS files in the portal that the site is not necessarily using, are they still being loaded? DNN has a skin.css, a portal.css, and a default.css on every portal. In addition, I have some skins loaded under the root that are not utilized by the portal, but they are there in case I wanted to use them later. Are they being read and are they slowing down the site (potentially)?

It is only downloaded if the page requests it but there is no way for the browser to know if you are going to use any of the content inside of the css file. If it is referenced by the page it will be downloaded (and will show up in the waterfall). If it is just sitting on the server but not referenced anywhere then it's not doing any harm.

Thanks for all the info on this. You've been a big help. Seems I've discovered that DNN has module called page blaster that automatically merges all javascript and CSS files into 1 file each and then somehow creates a copy of the pages and stores them on the server. This cache is updated periodically based on settings provided by user and needs. Having read all you've said it looks like a good way for me to shave off a couple of seconds. I spent a lot of money on the skin you commented on that has far too many images in it. I can hardly ask the developer to use sprites, but now I know what to look for - or to eventually create myself. I've learned a lot here.

Big Thanks!

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RE: How can I translate what all this means? - danacton - 09-07-2010 10:42 AM

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