As requested, fps_cap and fps_cap_limit options are now available to use in SomaDevLauncher.ini. fps_cap_limit will default to 60 so only need to add fps_cap=1 to the ini file under "[launcher]" key if want to cap to 60 fps.
Currently the fps cap is only applied while in-game and is not yet capping the fps on login and character selection (will patch the client again later to sort this out).