Why is .NET Dictionary FindEntry faster than simple loop?

I try to understand how .net C# Dictionary works. I always heard its search mechanism is fast.

While looking at the implementation i saw the following code. The following is the FindEntry function as show in: MSDN implementation

private int FindEntry(TKey key) {
        if( key == null) {
            ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
        }

        if (buckets != null) {
            int hashCode = comparer.GetHashCode(key) & 0x7FFFFFFF;
            for (int i = buckets[hashCode % buckets.Length]; i >= 0; i = entries[i].next) {
                if (entries[i].hashCode == hashCode && comparer.Equals(entries[i].key, key)) return i;
            }
        }
        return -1;
    }

Can someone please explain to me, why the above code is faster than a simple loop and simple check of the value? Example:

private int FindEntry(TKey key) {
        if( key == null) {
            ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
        }

            for (i >= 0; i = entries[i].next) {
                if (entries[i].key == key) return i;
            }
        }
        return -1;
    }