Decided to get it off of playsnowtopia.com as I saw a comment about it. IT WORKED and this is what I made (took a screenshot now just because it was about to crash, still building though, just VERY slowly)
Finally crashed after 92 runs and 1152 skiers... Had a great time playing a working version would send you a final product image but you know, it crashed. Although if you optimize this more I'd have an even greater time :D
I'd expect the game to give you way more experts than beginners with the amount of black ski runs you have :P
In the end, I had the same issues as you when I reached about 3k skiers... It was on the brink of crashing.