Pyroscope is an open source continuous profiling platform. It will help you:

• Find performance issues in your code
• Resolve issues with high CPU utilization
• Understand the call tree of your application
• Track changes over time

Lighthouse is an open-source, automated tool for improving the quality of web pages. You can run it against any web page, public or requiring authentication. It has audits for performance, accessibility, progressive web apps, SEO and more.

Vitess is a database clustering system for horizontal scaling of MySQL.

Nuster is a high performance caching proxy server based on HAProxy. It is 100% compatible with HAProxy, and takes full advantage of the ACL functionality of HAProxy to provide fine-grained caching policy based on the content of request, response or server status.

cAdvisor (Container Advisor) provides container users an understanding of the resource usage and performance characteristics of their running containers. It is a running daemon that collects, aggregates, processes, and exports information about running containers. Specifically, for each container it keeps resource isolation parameters, historical resource usage, histograms of complete historical resource usage and network statistics. This data is exported by container and machine-wide.

cAdvisor has native support for Docker containers and should support just about any other container type out of the box.

wrk is a modern HTTP benchmarking tool capable of generating significant load when run on a single multi-core CPU. It combines a multithreaded design with scalable event notification systems such as epoll and kqueue.

An optional LuaJIT script can perform HTTP request generation, response processing, and custom reporting.

webhint is a linting tool that will help you with your site's accessibility, speed, security and more, by checking your code for best practices and common errors. Use the online scanner or the CLI to start checking your site for errors.

PHP performance tool analyse your script on time, memory usage and db query. Support Laravel and Composer for web, web console and command line interfaces.

Shareable JavaScript Benchmarking

• Built-in ES2015 support, powered by Babel
• Statistically significant benchmarks, powered by Benchmark.js

Prepack is a tool that optimizes JavaScript source code: Computations that can be done at compile-time instead of run-time get eliminated. Prepack replaces the global code of a JavaScript bundle with equivalent code that is a simple sequence of assignments. This gets rid of most intermediate computations and object allocations.

Cheatsheet list of techniques and patterns for maximizing software performance and scalability

Run a free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds. You can run simple tests or perform advanced testing including multi-step transactions, video capture, content blocking and much more. Your results will provide rich diagnostic information including resource loading waterfall charts, Page Speed optimization checks and suggestions for improvements.

PPM is a process manager, supercharger and load balancer for PHP applications.
It's based on ReactPHP and works best with applications that use request-response frameworks like Symfony's HTTPKernel. The approach of this is to kill the expensive bootstrap of PHP (declaring symbols, loading/parsing files) and the bootstrap of feature-rich frameworks. See Performance section for a quick hint. PHP-PM basically spawns several PHP instances as worker bootstraping your application (eg. the whole Symfony Kernel) and hold it in the memory to be prepared for every incoming request: This is why PHP-PM makes your application so fast.

Performance is a feature. This book provides a hands-on overview of what every web developer needs to know about the various types of networks (WiFi, 3G/4G), transport protocols (UDP, TCP, and TLS), application protocols (HTTP/1.1, HTTP/2), and APIs available in the browser (XHR, WebSocket, WebRTC, and more) to deliver the best—fast, reliable, and resilient—user experience.

The easiest way to measure your performance budget.

The coach helps you find performance problems on your web page. Think of the coach as a modern version of YSlow. The coach will give advice of how your page can be faster.

New Relic’s SaaS-based Application Performance Monitoring helps you build, deploy, and maintain great web software.
Also, server monitoring, and more.

A lightweight JS framework for fast navigation and page updates from YouTube

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.