Lowering your in-game graphics settings can solve many performance and graphics issues. To do so, open the game's main menu and set your graphics quality to Low using the dropdown or slider. If you still experience slow gameplay, turn off all in-game sound and music from the options menu.
If you see a performance improvement with these settings, try raising or re-enabling them one at a time to determine the problem. Once you find the setting or combination of settings that reduced performance, leave them disabled.