Kotlin Performance Tuning: 20 Best Practices You Should Know

Performance is a critical metric that can make or break your application. While Kotlin offers a plethora of features to make development easier, knowing how to leverage them for performance can be a game-changer. This article provides 20 tips that will help you write high-performance Kotlin code.

Photo by Braden Collum on Unsplash

“The best performance improvement is the transition from the nonworking state to the working state.” — J. Osterhout

Basic Tips

1. Use val Over var

Favor immutability to make your code more predictable and easier to reason about.

val immutable = "I'm immutable"
// Using val makes the variable read-only, promoting immutability.

2. Avoid !! Operator

Use Kotlin’s null-safety features to avoid NullPointerException.

val length = someString?.length ?: 0
// Using safe calls and the Elvis operator to avoid NullPointerException.

3. Use when Instead of Long if-else Chains

It’s more readable and can be more efficient.

when(x) {
    1 -> print("x == 1")
    2 -> print("x == 2")
    else -> print("x is neither 1 nor 2")
}
// Using when is more…