Why is method slower in Python than in C# using the same dll?

I want to make a python code but it requires a lot of calculations. I thought it would be good to write some c#-based method and invoke the dll from python. For testing, I wrote some simple code (see below). Here is an example code in c#:

    namespace TestFrameWork
    {
        public class Class1
        {
            public static float Summ(float[][] arr, int rowsHeight, int colsWidth)
            {
                float value = 0;
                for (int col = 0; col < colsWidth; col++)
                {
                    for (int row = 0; row < rowsHeight; row++)
                    {
                        value += 1;
                    }
                }
                return value;
            }
        }
    }

And the test:

    namespace main
    {
        class Program
        {

            static void Main(string[] args)
            {

                float[][] inputs = Enumerable
                       .Range(0, 4000)               
                       .Select(i => new float[33000])  
                       .ToArray();                 

                var watch = System.Diagnostics.Stopwatch.StartNew();
                var result = Class1.Summ(inputs, 4000, 33000);
                watch.Stop();
                var elapsedMs = watch.ElapsedMilliseconds;
                Console.WriteLine(result);
                Console.WriteLine($"Elapsed time: {elapsedMs} ms");
            }
        }
    }

And the code for loading the method from Python:

import numpy as np
import clr
import time

w = 4000
h = 33000
image  = np.ones((h,w))
clr.AddReference(r"C:\Users\nagym\source\repos\TestFrameWork\bin\Debug\TestFrameWork.dll")
from TestFrameWork import Class1
image1 = image.data.tolist()
start = time.time()
result = Class1.Summ(image1,w,h)
print(f"Elapsed time c# : {(time.time() - start)*1000} ms")

Results:

VS C#  ->  Elapsed time:       318 ms
Python ->  Elapsed time c# : 24567.59548187256 ms

Using Visual Studio to run the C# code is much faster. But why? I am using the same DLL file.