As Arduino Uno has a 16 MHz oscillator but while running program it has less frequency because some of the processing power is used for running the program. I have used the delay(1) but it is giving me around 500 Hz.

My questions:

1. Is there any way to achieve more than 500 Hz?
2. What would be the maximum frequency of digital signal for below program?

void setup() {
  pinMode(13, OUTPUT);
}

void loop() {
  digitalWrite(13, HIGH);          
  digitalWrite(13, LOW);         
}