Its not painful if you arrive and depart from SVO2. You disembark, go to transfer desk, if an agent is there, give her/him your tickets and passport and she/he will take care of the rest, provide you with a borading pass, and off you go to the International transit zone. If there is noone at the desk, you wait there until someone shows up (sometimes a wait can be 30 minutes or so). Please remember you can only access C lounge 2 hours before your departure, so you will just have to hang out at a cafe/bar/shop until you can enter the lounge. Enjoy