Medic is generally the fastest. Some people have actually complained about it on the official forums and requested a nerf for gameplay balance. Speaking as someone who primarily plays recon, though, I think it's fine.
Non-Medic-Specific Notes
Below are a bunch of notes about level the Medic class, but here are a few for any class.
- Try to find nearly-full servers. When there are a few people on a map, it takes a long time to find each other. It also takes a long time to end the round, which is when you get a pile of bonus points for special actions. I prefer lightly-loaded servers, but it clearly hurts my points-per-minute.
- Understand bonus points. From the main game screen, explore Multiplayer > Weapons and Gadgets, and Multiplayer > My Stats. These show how you're doing on progress toward various awards, as well as stars for accomplishments on various weapons. Some of these awards will give 5,000 to 10,000 bonus points.
- Follow (and set) waypoints. If one of the objectives is marked with pointy things around it, go there. Not only is this good gameplay, concentrating your squad's resources on a given objective, but it also generates points for you and your team when you capture or defend the point, as well as bonuses at the end of the round if you do it enough. It disappoints me that people don't do this more. If no one on your squad has set a waypoint, point your weapon at an objective and use your spotting key to highlight it.
Medics: Points
Kyle's list of points is correct, though I can confirm it's 20 points for a squad heal. So you can see the big points are to be had through revives, which not only get you points but win back tickets for your team, extending your chances of winning.
Watch for Opportunities
Assuming you're not playing hardcore (which has no minimap): when a teammate dies, you'll see a white defibrillator line on the map; when a squadmate dies it'll be bright green. Force yourself to keep watching the minimap until you're always aware of people needing revives nearby.
As I recall you also see a white bandaid icon flickering above people in need of a heal, and a white cross on the map for people who have specifically requested healing.
Leveling Medics: The Dark Side
I've often been the victim of a medic who was either reviving without thinking, or was playing for points without regard for the team.
If someone goes down in a barrage of fire you can revive them, often from partial cover, then run back into hiding to heal yourself... and watch your "patient" get killed in the same killzone where they died just a moment before. This makes points for you, and doesn't hurt your team's tickets, but it counts as a death for your patient (besides cheesing them off... especially if you do it a second time).
I've seen some medics do this in a major massacre, racking up points but not really helping the team. Some might disagree, and it's always context-dependent, but I feel at a certain point you just become a ghoul, gathering points from victims' dead bodies. Sometimes you need to let people die so they can fall back, resupply, and regroup.
So think before you rez.
Leveling Medics: The Light Side
Dropping a healing crate in a killzone, though, is perfectly fair, and much appreciated. Then you're not being a ghoul, you're keeping people from being dead.
When I play medic I always go for the extended range perk, which doubles the radius of your healing pack. This is another win-win: it'll greatly boost your points, and really helps your team.
Best Answer
Download Fraps for free and it will allow you to display FPS and take screenshots etc. works for everything to my knowledge.