バイト配列を並列で0クリアしようと思ったんだが、なんかほぼ変わらない
なにか間違ってるんだろうか？

public static void Main()
{
var methods = new Action<byte[]>[] { ArrayClear, ConcurrentClear };
for (var i = 0; i < 5; i++)
foreach (var method in methods)
{
var sw = Stopwatch.StartNew();
var buffer = new byte[64 * 1024 * 1024];
var random = new Random(0);
random.NextBytes(buffer);
method(buffer);
Console.WriteLine(method.GetMethodInfo().Name + ": " + sw.ElapsedMilliseconds);
}
}

private static void ArrayClear(byte[] buffer)
{ Array.Clear(buffer, 0, buffer.Length); }

private static void ConcurrentClear(byte[] buffer)
{ var t0 = Task.Run(() => Array.Clear(buffer, 0, buffer.Length / 2));
var t1 = Task.Run(() => Array.Clear(buffer, buffer.Length / 2, buffer.Length / 2));
Task.WaitAll(t0, t1); }