PHP version 8.1 introduces many exciting new features, one of which is the Fibers extension, now built directly into the core. But what problems does this extension aim to solve? Does this mean there's no longer a need for async frameworks like Swoole or ReactPHP? In this talk, we'll explore the concept that concurrent execution doesn't necessarily imply simultaneous execution. We'll examine the advantages and disadvantages of so-called green threads. Most importantly, we'll evaluate whether it's worth the effort.