Performance Cost of Reflection in Go

Performance
2026-04-17T12:05:42+00:00
Reflection in Go is significantly slower than static code because it requires runtime type inspection, so avoid it in performance-critical paths.

Reflection in Go incurs a significant performance cost because it bypasses compile-time optimizations and forces the runtime to inspect type information dynamically. Use the reflect package only when static typing is impossible, such as in generic frameworks or serialization libraries, and avoid it in performance-critical loops.

// Avoid reflection in hot paths
func SlowProcess(items []interface{}) {
    for _, item := range items {
        // Runtime type inspection is expensive
        t := reflect.TypeOf(item)
        if t.Kind() == reflect.String {
            // ... logic ...
        }
    }
}

// Prefer static typing for speed
func FastProcess(items []string) {
    for _, item := range items {
        // Compile-time optimization applies
        _ = len(item)
    }
}