actually i experienced this on both of my computers the VERY FIRST TIME after each clean install, however i also found the solution:
annoying as this may be, just load up the game and go do something for a while... let it load in the menu and just wait it out.. eventually it will load all the way in and you can use the menu like normal.. play the game everything will be fine... next time you load up the game the lag will be gone, menus will work like normal... this only happens the first time, just be sure to let it load all the way in otherwise it is going to do this until you do.