Performance Tips

Prefer Interface Over Type for Objects

// Faster - cached by name
interface User {
  name: string;
  email: string;
}

// Slower - structural comparison each time
type UserType = {
  name: string;
  email: string;
};

Avoid Deep Recursion

// Can hit recursion limit
type DeepReadonly = T extends (...args: any[]) => any
  ? T
  : T extends readonly (infer U)[]
    ? ReadonlyArray>
    : T extends object
      ? { readonly [K in keyof T]: DeepReadonly }
      : T;

// Better: limit depth to avoid excessive recursion
type PrevDepth = [never, 0, 1, 2, 3, 4, 5];
type DeepReadonlyLimited =
  Depth extends 0 ? T :
  T extends (...args: any[]) => any ? T :
  T extends readonly (infer U)[] ? ReadonlyArray> :
  T extends object ? { readonly [K in keyof T]: DeepReadonlyLimited } :
  T;

Use Type Annotations

type ExpectedType = { value: number };
const data = { value: 42 };
const complexFunction = (input: { value: number }): ExpectedType => ({
  value: input.value,
});

// Slow - complex inference
const result = complexFunction(data);

// Faster - explicit annotation
const resultExplicit: ExpectedType = complexFunction(data);

Project Configuration

{
  "compilerOptions": {
    "skipLibCheck": true,      // Skip checking .d.ts
    "incremental": true,       // Cache compilations
    "tsBuildInfoFile": ".tsbuildinfo"
  }
}

Profiling

# Generate trace
tsc --generateTrace ./trace

# Analyze with:
# chrome://tracing or @typescript/analyze-trace

Type Checking Performance

Type Checking Performance

Performance Tips

Prefer Interface Over Type for Objects

Avoid Deep Recursion

Use Type Annotations

Project Configuration

Profiling