What are the details of your computer? Windows/mac/llinux? Graphics card? Etc.
For no-mods play you should not need to tweak anything to get much better than that: 8 fps points strongly to their being a major problem (almost no system of the past 5 years is too weak to run vanilla better than that). My recommendation would be to backup your game folder to somewhere else, redownload, and play without messing with anything. Also check to make sure the game is running on your graphics card, if the system has integrated graphics.