Optimize First Input Delay (FID)

The main cause of a poor FID is heavy JavaScript execution. Optimizing how JavaScript parses, compiles, and executes on your web page will directly reduce FID.

For a deep dive on how to improve FID, see Optimize FID. For additional guidance on individual performance techniques that can also improve FID, see:

• Reduce the impact of third-party code
• Reduce JavaScript execution time
• Minimize main thread work
• Keep request counts low and transfer sizes small