Alternative to Activator.CreateInstance

Using expressions, you can achieve a faster result with less code.
 

public static T New<T>()
{
    Type t = typeof(T);
    Func<T> method = Expression.Lambda<Func<T>>(Expression.Block(t, new Expression[] { Expression.New(t) })).Compile();
 
    return method();
}

 
Furthermore, this can be refined further by capturing the method into a dictionary and saving it off for future use. As an example, you can see this tip[^], which does something like this.
 
From my own testing of 1000 iterations of both, mine (without caching) was 148 milliseconds, while your original was 220 milliseconds.