def calculate_optimal_capability(capabilities):
    """
    Calculate the optimal capability based on its performance and efficiency.

    Args:
        capabilities (list): A list of tuples containing capability information.

    Returns:
        tuple: The optimal capability.
    """
    if not capabilities:
        return None
    
    optimal = max(capabilities, key=lambda x: x[1] / x[2])
    
    return optimal

# Example usage
capabilities = [('evolved_verified_generate_test_1768680667', 4235.89001196408, 51, 8305.7),
                ('verified_default', 4235.0, 51, 8303.9),
                ('evolved_verified_fib_fast_1769055768', 4235.0, 51, 8303.9)]

optimal = calculate_optimal_capability(capabilities)
print(optimal)