I'm starting the Steam edition of Painkiller again on a new comp and running into some issues that I am fairly certain are caused by too high of a framerate (enemies stuck on or falling through scenery and jerky physics, primarily). I'm wondering if there is a launch command that will do the job.

I tried using a /setmaxfps ## launch option as described in this post: http://www.gog.com/forum/painkiller_black_edition/fps_650/post7, but it had no effect. Has anyone successfully used a launch option to do this?

Is there an in-game option for vsync? Turn that on and your frames should be limited to your screen refresh rate. If there is no in-game option for it then you can force it on with your graphics card driver software, but I'm sure this game has a vsync option.

I was able to enable v-sync in my nvidia control panel (no in-game option that I could find), however the problems are still there.

I had thought that v-sync does not actually limit the framerate to my monitor's refresh rate, but merely limits it to a multiple of the refresh. In other words, if Painkiller runs at 200 FPS on my 60 Hz monitor with v-sync disabled, then enabling v-sync would cut the framerate to 180 FPS (180 being an even multiple of 60). Do I have that wrong?

That seems logical to me, because I have played several games that have both an in-game v-sync option and an in-game framerate limiting option, so there must be a functional difference between the two.

Done some searching around and indeed, there doesn't appear to be a vsync option in the game itself and that you have to force it on for that program via the driver software (e.g. nvidia Control Panel, ATI Catalyst).

I remember that Painkiller Black used to have the issue where load times were tied to framerate so with vsync on the game took longer to load up levels. That got fixed with the Universal Update 1.0.1. However, as you say, physics are tied to framerate (some old games used to do that and modern machines have issues with them now), so you need to cap the framerate. Vsync should do that, but it might be worth finding out what the original intended framerate the game was designed for.

I've checked to see what I can find about vsync, and can only confirm what I thought about it, that it caps your framerate to your screen refresh rate. So on a 60Hz LCD, even if your GPU is capable of running a game at a million FPS, it would cap it to 60. This is what I've always been led to believe vsync does (well, and that it does strange things if the game is running below the refresh rate, so you should turn it off if this is the case).

I think there may be issues later on in the game though. Some of the forum posts here mention a bridge (can't remember if it is main game or expansion, but I've not gotten around to playing it myself yet) where due to the fast framerate tied to physics, the bridge bounces up and down too much and throws you off it to your death.

That would be Chapter I level 3, Catacombs. The very same bridge apparently may corrupt saved games as well.
I never had any issues using /setmaxfps 60 in the in-game console.

Specifically, in-game you can type ~ to bring up the console, then type setmaxfps 60 followed by Return/Enter, and ~ again to close the console. This should fix anything where the physics were going crazy due to excessive frame rates (such as the infamous bridge).

I think this will help.