Slow speed on Duo (Arduino)?

Am I doing something wrong? I seem to get pretty low speeds when using the 700mhz core in the Arduino IDE.

/*                Results
   -----------------------------------------
  |         Board           |     Time      |
  |-----------------------------------------|
  | ESP32 Dev (240mhz)      |      183      |
  | Nano Connect (150mhz)   |      334      |
  | Raspi Pico (150mhz)     |      335      |
  | Raspi Pico W (150mhz)   |      335      |
  | Nano Connect (133mhz)   |      377      |
  | Raspi Pico (133mhz)     |      378      |
  | Raspi Pico W (133mhz)   |      378      |
  | Nano Every (16mhz)      |     7412      |
  | Milkv Duo 64 (700mhz)   |     8073      |
   -----------------------------------------
*/

#include <Arduino.h>

unsigned long startTime = 0;
unsigned long endTime = 0;
unsigned long elapsedTime = 0;
unsigned long fibonacciValue = 0;

void setup() {
  Serial.begin(115200);
}

void loop() {
  startTime = 0;
  endTime = 0;
  elapsedTime = 0;
  startTime = micros();
  yourFunction();
  endTime = micros();
  elapsedTime = endTime - startTime;
  Serial.print("Elapsed Time (microseconds): ");
  Serial.println(elapsedTime);
  delay(10000);
}

void yourFunction() {
  for (volatile int i = 0; i < 20; ++i) {
    fibonacciValue = 0;
    fibonacciValue = fibonacci(10);
  }
}

unsigned long fibonacci(int n) {
  if (n <= 1) {
    return n;
  } else {
    return fibonacci(n - 1) + fibonacci(n - 2);
  }
}