Use The Index, Luke! : A tutorial covering SQL indexing and SQL tuning for developers: avoiding unnecessary details about database internals.
SQL indexing is the most effect...
MySQLTuner : MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stabi...
re:dash : Query Editor: think of JS Fiddle for SQL queries. It's your way to share data in the organization in an open way, by sharing both the dataset and the ...
Dex : Dex is a MongoDB performance tuning tool that compares queries to the available indexes in the queried collection(s) and generates index suggestions b...
Vitess is a database clustering system for horizontal scaling of MySQL.
Minimize round-trip times : An article on the best practices to apply in order to minimize HTTP round-trip times
Let's make the web faster : There are many ways to make websites run faster. In this section, you can discover performance best practices that real web professionals employ in th...
Seashells : Seashells lets you pipe output from command-line programs to the web in real-time, even without installing any new software on your machine. You can u...
NGINX Unit : NGINX Unit is a dynamic web application server, designed to run applications in multiple languages. Unit is lightweight, polyglot, and dynamically con...
WebPagetest : Run a free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds.
Nice write-up on techniques for scaling up a web application.