Alright, I think I'm done tinkering with the ROM, here's what I've found (this is all on an A1 with 256MB swap):
Besides the default Trebuchet launcher, there are two free launchers with ICS aesthetics on the Play Store: Nova Launcher and Apex Launcher. Of the two, Apex Launcher runs faster IMO and it has a built-in hard-to-kill option as well (it works, too!). I'd recommend immediately downloading Apex Launcher and removing the built-in Trebuchet launcher (via TitaniumBackup) as soon as possible for any A1 user.
Forcing GPU rendering does not affect performance in any way, at least according to my tests. The difference in benchmark scores (I used all three SmartBenches and NenaMark1) was minimal at best (<0.1%) and I did not see any difference when running proper apps (both benchmark and perceived performance was unaffected).
Chainfire3D's driver causes graphical artifacts and constant hard reboots, DO NOT INSTALL IT!
Your device will run noticeably slower for a few minutes after every boot. Be patient, let it "warm up" a bit, and it'll start running smoothly. I really have no explanation for this, other than the system moving a whole lot of stuff over to the swap partition after boot (reading and writing to SD swap is slower than reading and writing to RAM).
For some weird reason, AutoKiller settings will occasionally seem to reset after a reboot, but the program will freeze up the device and after another reboot, settings will go back to normal. That being said, AutoKiller settings do make a difference: set them to the Aggressive preset (or high performance gaming, or whatever) and make sure you have all 10 kernel tweaks turned on (that is, if you are using the AutoKiller Memory Optimizer app to set AutoKiller settings). Just remember to make your launcher hard-to-kill.
As I suspected from experience with previous ROMs, zRAM (or Compcache) is a bad idea: enabling it creates a significant drop in both benchmark and perceived performance. Though on paper, it should increase your available RAM, this does not translate into better performance in the real world; rather, because your RAM is compressed, any reads or writes to it will take longer. You should only enable zRAM if you don't have a large enough Swap partition and/or you plan on running an app with huge RAM requirements. Even if you do enable it, try to set it to the lowest possible setting: the higher the compression, the bigger the hit on speed.
IMO, Best CPU governor is SmartassV2. Lagfree comes close, but SmartassV2 doesn't have a "warm-up time". Only choose Scary if battery life is more important to you than performance (it delivers the same battery life as Conservative, but with a smidgen of better performance).
This ROM doesn't like you rebooting it while it's plugged into a PC. Might be a bug or something, but rebooting the device while plugged into a PC frequently caused the device to freeze soon after, while rebooting the device without plugging it in never did such a thing.
I could still mess around with Swappiness, but I've gotten tired, so here's what I've found out: setting it to around 50 caused noticeably slower performance, while setting it to around 10 caused certain background apps to die more easily. In the case of a foreground app that uses a lot of RAM, even the hard-to-kill launcher died when Swappiness was set to 10. I recommend people experiment on their own if they want to, but otherwise, set it somewhere between 25 and 35. Remember, too high swappiness causes general slowdown, while too low swappiness causes background apps to be killed faster, as well as increasing the possibility of a foreground app dying or a soft reboot happening.
Obvious tweaks I'll only mention without description because people have mentioned these before me: set your SD Readahead to at least 1024 (mine's at 2048), have a Swap partition of 256MB if you're on an A1, set touchscreen sensitivity to 25/50 (sensitivity/noise; this one only increases perceived performance, as it will increase apparent touchscreen responsiveness), enable custom SVS and set the values to the suggested ones (if you know what you're doing, you can mess around with the settings), make sure to set SVS to apply at boot, decrease animation scale in the developer options (will increase animation speed), set your launcher's minimum animation speeds to a setting that seems smooth, but still flashy (perceived performance). In the Performance options, disable Surface Dithering, enable 16bit transparency, check both boxes in Memory management (but leave zRam disabled!), and change your governor and your Maximum CPU frequency based on personal preference/experience (with the suggested custom SVS, the most frequent highest clock speed is, AFAIK, 1113 Mhz, but make sure to test it out before checking the Set at boot option).
One more thing: there are certain apps (like DSP Manager or Google Talk) that automatically run services, even if you aren't running the apps themselves. This means that as long as you have the app installed on your device, in most cases, its service will be running in the background along with other services (it's kind of complicated, to the point where even I don't understand it fully). Though in most cases, these barely affect overall performance, certain poorly written apps' services consume a noticeable amount of RAM and/or processing power, thereby slowing down your device simply by being installed. And there is a certain, very poorly coded (IMO) app out there that is also extremely popular, and I know from personal experience that uninstalling it will noticeably speed up your device. Go ahead, uninstall the Facebook app, you'll see what I mean...
zRAM sucks, Swappiness between 25 and 35 is good, SmartassV2 is best CPU governor, avoid Chainfire3D, Force GPU Rendering does nothing, Apex Launcher is the best ICS launcher ATM, set the AutoKiller settings to Aggressive, don't reboot with your phone plugged into your PC, let your phone sit idly for a minute after a reboot, and uninstall the Facebook app if you have it.
If you're getting reboots, it's probably due to your Memory settings. Yes, you pretty much need a 256MB Swap if you're running on an A1, but check your Swappiness, your Memory management settings (disable zRAM if you have it enabled!), and your AutoKiller settings (if you have an app to check them; if you don't, I recommend AutoKiller Memory Optimizer). Though I did get some hard reboots when automatically restoring apps via TitaniumBackup Pro, I haven't had any since, and I've been using my device quite a bit.