the thread starter wants a direct answer. and this will be helpful to all of us.

and not complaints about the performance and not attacks and reminders about not buying it etc. and not facts about how device is slowing down as you put in more and more applications.

ok I'll give you a direct answer that I know:

-overclock your N900
-install transitioncontrol (faster transitions improves performance)
-install softwares already available that will make your life easier like:
>shortcutd (lets you set camera button to a function eg. call)
>simple brightness app
>quick launch
>call notify
>catorise
>cpufrequi
>headphone daemon
>live focus (improves the performance and functionality of your camera)
>mplayer + SIB (play unplayable video format, really amazing)

I might not have mentioned everything the rest can add up!

I also read somewhere that the index trackerd can sometimes get a bit stuck, for example when encounters certain file extensions... possible something to do with file association and particular issues around codec.

In fact this index tracker is one of the processes that is always around, this by itself comsumes energy, does anyone know what would happen if it was turned off?

Just gotta point this out: Most transitions tweaks don't actually change performance at all - what they change is how quickly certain animations play, which, with the right combinations of visual effect, they make people feel things are going faster/better/smoother when they are actually the same.

What performance gains you get is setting rotation animations down to all zeroes, for instance (which isn't truly performance, but it cuts the time to rotate down... by, like, a barely perceptible difference from the transitions I was using beforehandc), and/or dropping the amount of iterations of "blur" on background stuff when a menu pops up, etc (which may or may not actually noticeably change anything performance wise, and unless you're pushing your device or catch it during heavy RAM/swap IO it shouldn't change anything, although I have noticed a slight purely psychological effect in that switching from more blur to significantly less or none [especially none] gives a perceived UI 'crispness' that seems to in turn give the illusion of graphical performance being better.)

I know that the thread is old (being most of a year ago is tricky for the ones that read just the start of the date but in this topic got amazed how much improved things with time.

Got my phone more or less by the time this thread started, and did a lot of tests, installs, configurations and so on with time, so was getting a bit of garbage all around.

Last week decided for a mostly fresh restart, and reflashed, applied pr1.3, powerkernel, cssu, n900tuneup and swappolube (but not restored configurations, in fact deleted most "." dirs in user home), and got amazed how fast it felt compared with my memories of the start, and how much i can abuse battery, seeing that it can last more than a day even with that.

So my answer for the original question is the community, participating, keeping in touch with what is going here, testing things and helping if you can. You will be surprised with how much better device you will have thanks to that.