I have a partitioned drive on my MBP, and an install of Snow Leopard (10.6.8) that I still use periodically. Every time I switch back to Yosemite I get irritate

I have a partitioned drive on my MBP, and an install of Snow Leopard (10.6.8) that I still use periodically. Every time I switch back to Yosemite I get irritated by the way it makes my machine seems slightly but noticeably less responsive. After a few hours I just get used to it. But when I switch back to Snow Leopard I always notice that everything feels quicker and more solid. I also find that once I'm in Snow Leopard, I tend to stay there until I actually need something on the Yosemite side. Don't get me wrong, there are a lot of nice touches and features in Yosemite that I like. And I've never had problems with crashes, or really any serious issues. I just wish it didn't feel quite so bloated.