Ref/Invoke via reflection

Main.java

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;

public class Main {

  public static void main(String[] args) throws Throwable {
    ArrayList<String> ref = new ArrayList<String>();
    ref.add("public class Ref {\n");
    ref.add("  public static void main(String[] args) {\n");

    for (int i = 0; i < 5_000; i++) {
      ref.add("    new s.S" + i + "();");
      Files.write(Paths.get("src/s/S" + i + ".java"), ("package s; public class S" + i + "{}").getBytes());
    }

    ref.add("\n  }\n}");

    Files.write(Paths.get("src/Ref.java"), ref);

    measure(() -> Ref.main(args), "Ref");
//    measure(() -> { for (int i = 0; i < 5000; i++) Class.forName("s.S" + i).getConstructor().newInstance(); }, "Inv");


  }

  private static void measure(ThrowableRunnable run, String what) throws Throwable {
    long start = System.currentTimeMillis();
    run.run();
    long end = System.currentTimeMillis();
    System.out.println(what + ":" + (end - start));
  }

  public interface ThrowableRunnable<T extends Throwable> {
    void run() throws T;
  }
}