how can I get better latency on xp mc

[nem0nic]

But again, even with your caveat you're talking about optimizations that need to be programmed towards. If the application you're running doesn't specifically take advantage of them, you see no increase. Using multicore as an example, MANY people saw performance drops when they went from a P4 based computer to a C2D based machine because even though the C2D was multicore, each core was clocked lower (as was the mainboard's FSB). When combined with the fact that the application didn't specifically take advantage of multicore hardware, performance suffered.

And when you add to that the fact that Vista is overall less efficient than XP when it comes to most tasks, you end up with a net loss in performance.

Of course, if you're running a DAW that is written to take advantage of a 64bit OS and with Windows audio in mind (like Sonar), then the benefits are clear. But the promise of audio engine optimizations in Vista (like WaveRT) still haven't been adopted by many developers.

If you are able to pick only programs that were written for a 64bit OS, run hardware with 64bit drivers (digitally signed), and turn of all the eye candy and unnecessary crap (like Aero), then it's possible to see a net gain in performance using a 64bit OS.

[Monika.mhz]

Again, i'm really trying to narrow the 64-bit discussion down to just a question of MIDI, which is where I see the biggest performance gains. (the MIDI driver in 64 vista sp1 has been specifically designed with performance, jitter, and latency in mind) The reduction in pre-software problems is astounding.

While you may not see a performance increase in traktor itself, you WILL see an overall reduction in latency/jitter, if your MIDI controller sees less latency/jitter OS side, right?

Less congestion as well thanks to a faster pipe to that processor. So while you MIGHT run into higher DPC latency(I experience less in 64-bit), you'll still still end up with a net gain with a jitter/latency reduction.

[nem0nic]

the MIDI driver in 64 vista sp1 has been specifically designed with performance, jitter, and latency in mind

The WaveRT MIDI driver is, but most of us aren't actually using a WaveRT interface with our DJ application. And without it, the default MIDI driver in Vista is even more limited then it is in XP. Fire up Vista and show me your hardware MIDI mapper for instance.

I'm certainly happy that you're home studio is doing well with Vista, but understand that much like the people who get on TV and tell us that they lost 100lbs eating SlimFast, your results are NOT typical. And anyone who spends 30 minutes searching Google or talking to a studio engineer can corroborate this fact.

As far as DPC latency goes, if you're getting lower DPC in Vista, it's because you didn't tweak your XP machine. I can spend 10 minutes tweaking my Boot Camped MBP or Dell Inspiron and take it from an every day driver to double digit DPC. Let me see that kind of DPC on your Vista machine.

Until all of our DJ applications and device drivers are WRITTEN for 64bit, there isn't a performance benefit going to a 64bit OS. And in the case of Vista specifically, it's almost always a detriment.