Performance is the bedrock of every modern application. But the technology landscape has evolved in a way that it has siloed all custodians of performance management. This book brings them all together on the same page. It is not a technical sermon. There are enough manuals for that. This is a book about changing how we think about performance. It’s about communicating to product managers why lazy-loading above-the-fold components matters. It is about helping engineers see how UX micro-interactions can impact the perception of speed. It will show QA teams why test cases should cover real-world devices, not just ideal scenarios. And finally, this book will help founders realise that performance isn’t a one-time fix, it’s a cultural habit.