Skyscraper Solver

So folks,
I removed the last bugs and cleaned up the code faster than I thought - so my Skyscraper solver waits to be downloaded from my site :-)
But unfortunately it is pretty timeconsuming to check if a solution is valid so it's quite slower than I thought! For example to go through all possibilities in a 6x6 quest with my backtracking algorithm can take several minutes in the worst case - even on my new laptop! That's bad - but I don't see many places for optimization which would really speed it up.
Of course this makes me thinking about another approach: it is possible and worth the time to solve it with Dancing Links like a Sudoku quest? Well, in fact I don't know and I didn't (and won't) try it. That's not an exercise which could be easily solved in a few hours in my opinion! But if anybody will do it and succeed, mail me please! I would be very interested in it.
So far so good. It's Friday afternoon, I have already done everything I had to do - it's time to relax and waiting for the weekend to begin :-)
Greetz, Sunshine