severance package

not clear how bad the situation is. But I heard from friends that some companies also offer severance even if the employee is let go based on performance. the severance is really not company being nice offering employee any benefit. It is a contract that employees promise they will not sue company for any reason, if they take the severance. practically a buy-out. so in some big companies, even if the employee is fired, as far as it is not resignation, they offer severance to ensure no law suit in the future.
Having that said, have you received any oral or written warning, telling you to improve certain things in certain time frame? Usually there is a standard process to go through in big companies.