PHP 8 is significantly faster and more memory-efficient than PHP 4 or even PHP 7. How to Install the Current Version of XAMPP XAMPP Installers and Downloads for Apache Friends
If you are looking for "4," you are likely looking for one of two things: download xampp 4
While it is possible to find old installers, using a "XAMPP 4" or any PHP 4-based stack is highly discouraged for modern development: PHP 8 is significantly faster and more memory-efficient
If you specifically need PHP 4 for an ancient project, you can find Old XAMPP Files on SourceForge under the "OldFiles" or version 1.x directories. Why You Should Use XAMPP 8.x Instead of PHP 4 download xampp 4