.NET testing framework with parallel testcases

I have unit tests in my C# project (VisualStudio 2015,Nunit). I want to check methods in many different situations with different parameters, to achieve that, i used TestCases. Each test method works very slow - few seconds, and TestCases count in my projects grows.

So now testing takes some minutes. I tried to parallel these tests, by moving each test to separate TestFixture - Nunit allows to run TestFixtures in parallel - Nunit Documentation. It slightly changed situation, but not significantly. I want to parallel tests not on the TestFixture level, but on testcases level. I don't know how to do it. I have read documentation for Nunit, Xunit, MBUnit etc. and didn't found the answer.

How can i run my tests in parallel, in such way that testscases will run simultaneously? Which framework to use?

My tests example:

public static class GeneralTestCases
{
    public static IEnumerable TestStoresCredentials
    {
        get
        {
            yield return new TestCaseData( ... ).SetName("incorrect password");
            ...
            yield return new TestCaseData( ... ).SetName("incorrect login");
        }
    }
}

[ TestFixture ]
[ Parallelizable ]
internal class GetProducts : BaseTest
{
    [ Test ]
    [ TestCaseSource( typeof( GeneralTestCases ), "TestCases" ) ]
    public void ReceiveProducts( TestCase case )
    {
        // ------------ Arrange
        var service = CreateService( case.User, case.Key, ... );

        // ------------ Act
        var serviceResponse = service.GetProducts(case.SpecialType);

        // ------------ Assert
        ...
        serviceResponse.Message.Should().NotBeNullOrEmpty();
        ...
    }
}


[ TestFixture ]
[ Parallelizable ]
internal class GetOrders : BaseTest
{
    [ Test ]
    [ TestCaseSource( typeof( GeneralTestCases ), "TestCases" ) ]
    public void ReceiveOrders( TestCase case )
    {
        // ------------ Arrange
        var service = CreateService( case.User, case.Key, ... );

        // ------------ Act
        var serviceResponse = service.GetOrders(case.SpecialType);

        // ------------ Assert
        ...
        serviceResponse.Message.Should().NotBeNullOrEmpty();
        ...
    }
}