boomerang is a piece of javascript that you add to your web pages, where it measures the performance of your website from your end user's point of view. It has the ability to send this data back to your server for further analysis. With boomerang, you find out exactly how fast your users think your site is.
InstantClick is a JavaScript library that dramatically speeds up your website, making navigation effectively instant in most cases.
Dex is a MongoDB performance tuning tool that compares queries to the available indexes in the queried collection(s) and generates index suggestions based on simple heuristics.
Online test to help speeding up heavy web pages
Chrome extension for detecting and simulating frontend Single Points Of Failure. Detects likely third-party single points of failure as you browse and allows you to Simulate 3rd party resources being unavailable.
Also, here: https://chrome.google.com/webstore/detail/spof-o-matic/plikhggfbplemddobondkeogomgoodeg
Blackfire Profiler automatically instruments your code to gather data about consumed server resources like memory, CPU time, and I/O. But Blackfire Profiler is more than figures; its interactive Callgraphs make it straightforward to find bottlenecks and improve performance. Moreover, profile comparisons let you understand the impact of your changes.
PhantomJS-based web performance metrics collector and monitoring tool
YSlow for PhantomJS
Rich tools for instrumenting, analyzing, and visualizing web apps.
A CLI tool for detecting frontend SPOF, mainly blocking scripts and CSS
A tutorial covering SQL indexing and SQL tuning for developers: avoiding unnecessary details about database internals.
SQL indexing is the most effective SQL tuning method and requires the same care as schema design yet it is often neglected during development. Use The Index, Luke explains SQL indexing from the source code perspective—covering ORM tools like Hibernate and Doctrine.
Smaller, Lighter, Faster, more modular jQuery - include only the parts you want! Don't use it, Don't include it.
MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability.
Sitespeed.io is an open source tool that helps you analyze and optimize your website speed and performance based on performance best practices. It collects data from multiple pages on your website, analyze the pages using performance best practices rules and output the result as HTML-files or JUnit XML.
Tool for finding memory leaks in JavaScript programs.
An article on the best practices to apply in order to minimize HTTP round-trip times
Run a free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds.
It displays a menu with links that load other bookmarklets including Firebug Lite, Page Resources, DOM Monster, SpriteMe, and CSSess. The Mobile Perf menu is updated as new bookmarklets are released - so you get the latest tools automatically.
There are many ways to make websites run faster. In this section, you can discover performance best practices that real web professionals employ in their everyday work. These practices have improved the user experience for millions of users and we hope they are useful for other web developers.
JavaScript performance tips article