Using the openBVE 2 Renderer Demo with the same 600m viewing distance, I get 250 fps at the location featured in the above screenshot (between Hemel Hempstead and Berkamsted).

Of course, 30 fps is just fine, and anything over around 60 fps is unnecessary (60Hz being a common monitor refresh rate), but if my computer can do better than 60 fps, it means that I have performance reserves which I could use for more route detail, or exterior car objects, etc. Normally I have VSync (vertical synchronisation) enabled, which limits my framerate to my monitor's refresh rate, so I get 60 fps most of the time. A visible set of heavily detailed exterior car objects in particular, can still have quite an impact on my framerates in openBVE 1, though.
I always build my own computers and choose the components carefully, and my latest includes a 3GHz Core 2 Quad Q9650 CPU (but a dual core CPU with the same clock speed would likely be just as good), NVIDIA GeForce GTX 260 graphics card, and 6GB DDR2 RAM (although 2 to 4 GB is just fine). I wanted this to be the best computer I've ever had, and it was built to last me a few years before I felt the need to upgrade again, and so that I could get good performance in modern games, including openBVE. It's actually exceeded my expectations.