Really depends on how you build. I tend to create large, VERY detailed parks, something that PC struggles with, especially if, like in my park, you use a lot of water effects even while paused and closed. I had about 2/3rds of the park filled when the fps started dropping like a rock from the average of 17 fps down to 4 fps. So I made multiple copies of the bench, then had each of those concentrate on just part of the park while I deleted anything that couldn't be seen of the rest of the park. Went back up to 17-18 fps but, but after a short time I was back down to 4 fps. Frustrating.
I've just been messing around on a much smaller park bench lately, and even it is running around 25-30 fps but slowly dropping, and there's only a couple rides and the park closed. My specs are a lot lower than yours (i7-2600, GTX 650 Ti with 16GB RAM), and the graphics are set lower.
Surprisingly I was able to download and open Fisherman's monster park file. 4 fps and I couldn't actually ride anything because of the lag, but it did open. LOL!