laggy as hell

[plutomaniac]

Although the errors are still there, that's good. With that trick you make the game recreate the configuration files and settings. Maybe steam corrupted them somehow. There are some errors though that usually indicate not updated graphics card drivers or drivers that do not work correctly. Can you reinstall the latest catalyst just to make sure? After that, try the file integrity check now again, it might solve everything. If not then at least it does not lag anymore and the game can be played.