Low-level languages, like C, have low-level memory management primitives like malloc() and free(). On the other hand, JavaScript values are allocated when things (objects, strings, etc.) are created and "automatically" free'd when they are not used anymore. The latter process is called garbage collection. This "automatically" is a source of confusion and gives JavaScript (and high-level languages) developers the impression they can decide not to care about memory management. This is a mistake.

This tutorial explains how to use the Heap Profiler for uncovering memory leaks in your applications.

"I know I should look at Chrome's Timeline panel, but what do I do with it?"

File this presentation under “I wish I’d been there in person.” Cliff Crocker, Aaron Kulick, and Balaji Ram joined forces at February’s SF Web Performance Meetup to tell a RUM (real user monitoring) story through the lens of three job functions at Walmart.com: the performance data analyst, the developer, and the business analyst.

80-90% of the end-user response time is spent on the frontend.

I’ve been recently working on optimizing performance of a so-called one-page web app. The application was highly dynamic, interactive, and was heavily stuffed with new CSS3 goodness. I’m not talking just border-radius and gradients. It was a full stack of shadows, gradients, transforms, sprinkled with transitions, smooth half-transparent colors, clever pseudo-element -based CSS tricks, and experimental CSS features.

But using SSL, just for the fun of it, is not a good idea. SSL impacts web performance negatively in several ways:

This article is my attempt at explaining what is going on at a high-level when you do $(). The code samples below are largely simplified from the actual jQuery/Sizzle source. If you find any inaccuracies or a point you would like further clarified, please let me know on twitter! Thanks!

JSlim is a JavaScript optimizer based on the Google Closure Compiler, but instead of optimizing your code it optimizes the code you use.

Most websites use JavaScript libraries like JQuery or Prototype, but they don't use the whole library. JSlim builds you a new version of your favorite JavaScript library with only the code you're using.

For traditional pages where the user is encouraged to navigate from page to page, memory leaks should almost never be a problem. However, for any page that encourages interaction, memory management must be considered. Most realize that ultimately if too much memory is consumed the page will be killed, forcing the user to reload it. However, even before all memory is exhausted performance problems arise:

When brainstorming alternatives, we found what seemed to be an obvious solution: the image Data URI scheme. It works in all major browsers (except IE6 and IE7), and it solves our problem of too many HTTP calls. The code looks like this:

This article will try to give you the tools and techniques to work on improving the experience of your own application.

One of the first systems our engineers built in AWS is called the Chaos Monkey. The Chaos Monkey’s job is to randomly kill instances and services within our architecture. If we aren’t constantly testing our ability to succeed despite failure, then it isn’t likely to work when it matters most – in the event of an unexpected outage.

It's a debugger for web pages, like FireBug (for FireFox) and Web Inspector (for WebKit-based browsers), except it's designed to work remotely, and in particular, to allow you debug web pages on a mobile device such as a phone.

How fast does your webpage load?

It indexes all the elements and their classes, and then--class by class--it removes one, and times how long it takes to scroll the page. Classes that save a considerable amount of time when removed indicate problem areas.

A number of people asked about the technical aspects of the great Delicious exodus of 2010, and I've finally had some time to write it up. Note that times on all the graphs are UTC.

Just because you didn’t get to go to that awesome conference doesn’t mean that you can’t still watch the lectures! Each weekend, we’ll feature a recommended web development lecture on Nettuts+.
This presentation, by Stoyan Stefanov and Nicole Sullivan, primarily details the huge performance benefits to using Object-Oriented CSS, as well as a crop of other common CSS hurdles.

We spend a whole lot of time making shit flashy and making it feel fast. That’s good, it provides a more pleasant user experience. But it should never be disingenuous. Sometimes it takes a second or two for an operation to complete.

This past weekend, I had the opportunity to speak at WordCamp Chicago. The topic I presented, “Making WordPress Faster: Front-end Performance Tips,” was a introduction on how to analyze and speed up websites built with WordPress.

Paul Irish presentation on jQuery performance.

Is there a decent on-the-fly JS compressor implemented in PHP? The only thing resembling this that I was able to find was Minify, but it's more of a full-blown compression solution with cache and everything. I want to keep the files separate and have the minimised files follow my own naming conventions, so Minify is a bit too complex for this purpose.