Optimized Program for Prime number in c#

public bool IsPrime(int x)
{
if (x == 2 x==3)
return true;
else
if (x % 2 == 0 x < 2 x % 3 == 0)
return false;
Double t=Math.Sqrt((Double)x);
for (int i = 3; i {
if (x % i == 0)
return false;
}
return true;
}