Dezalgo removes "deasync" usage from Node.js code. Deasync makes asynchronous operations synchronous, which blocks the event loop and is bad practice. Dezalgo identifies and eliminates these instances, replacing them with proper asynchronous alternatives. This improves application performance, stability, and responsiveness. It's essential for maintaining a healthy Node.js codebase and avoiding common performance bottlenecks related to blocking operations. Use dezalgo to sanitize old codebases or prevent future deasync introduction.