Measuring OS X Performance

I have a Late 2008 Unibody 15" Macbook Pro. Here's a little more detail:

My list of login items looks like this:
- App Tamer
- GrowlHelperApp
- iTunesHelper
- Path Finder
- HazelHelper
- Default Folder X Helper
- Launchbar
- CheckUpAlert
- Choosy
- Watts
- Dropbox
- Blast

For one thing, games perform terribly. And they used to work quite well! I played through all of Mirror's Edge on this machine and everything was silky smooth. Same with COD5 *and* 6, though I do realize those games were very well optimized and designed from the start to have high frame rates. I also played through Dead Space on this.. the performance wasn't as great as on the other titles mentioned but it was absolutely playable and fun.
Now, when I run Amnesia: The Dark Descent or Starcraft II, the performance is absolutely terrible. In Starcraft II I get less than 10 FPS and in both games, I noticed a strange effect. The performance fluctuates. It will run smoothly for about 2 seconds, then the frame rate goes to slideshow-level for about 2 or 3 seconds, then back to smooth, back to bad, ad infinitum.

I did what anyone would try as a first step and killed all apps, especially windowed apps but also background apps that shouldn't really make a difference normally.

I disabled iStat Menus, Hazel and quit Path Finder, Safari, NetNewsWire, Dropbox, Default Folder X, App Tamer, Watts and, well, just about everything that isn't system related. Low and behold.. Starcraft II was suddenly super smooth.. and that with all graphics related settings completely maxed. (A fact rendered all the more stunning when considering that the Starcraft II- suggested settings were a mix of "medium" and "low" for graphics and a screen resolution of something just over 1000xSomething pixels).

Since I disabled or quit just about everything, I have no way of knowing which program was causing the terrible performance.

Does anyone know of an app that can record performance statistics? I'd like to start performance recording, then launch a game and let it run for a bit, then quit and look at the recorded performance data. This could give me a clue as to what is causing the significant performance drop while running high-performance 3D graphics applications such as games.

If I had to guess, I could imagine App Tamer, Blast and perhaps even iStat Menus being problematic. Blast is very handy but has to keep track of what the latest files are that are being opened by keeping a running list of accessed files. I could see this impacting performance when playing a game.

App Tamer is relatively simple but it's also a very young app. It was released a very short time ago and is still barely above 1.0. While it is an app designed to IMPROVE performance by pausing background apps automatically, ironically it could also be the cause of performance problems with apps that don't expect to be paused, for example. It even includes a "gaming mode" that instantly pauses all apps not presently in the foreground.

iStat Menus has been around for a long time and I'd think it's mature enough to not cause performance problems. The only reason I could imagine this being the culprit is because by nature, it has to continually poll the system for the latest hardware sensor data. I could imagine this causing a hit on performance as well, though it's hard to tell how significant that would be.

Anyway.. apologies for this lengthy post. It's frustrating to suddenly have a system that I *know* could perform well perform this poorly. And I want to find out why. A performance monitoring app such as the one I asked about earlier would be a great first step, I think. Any other suggestions or comments are welcome!

 

It's 320 GB and I currently have 153 GB of free space.

 

I know how to use Activity Monitor. The thing is that I'd like to know what's happening in terms of performance WHILE a game is in progress. Hence the question about a way to monitor and record performance data while the game process is executing.