You can assume that latency on Windows XP (I do not know as much about Vista) is governed by these facts:

Ordinary Windows audio has a built in unacceptable latency.

DirectX drivers have at best about 20 millisecond latency -- borderline, not really usable if phrasing or rapid performance are your forte.

Kernel mode drivers supplied by interface vendors have excellent latency.

ASIO drivers supplied by interface vendors have excellent latency.

In short, it's not the PCI bus, but if you are serious about real time on Windows you must have either an ASIO driver or a kernel mode driver. You can probably tell what the driver is from the Control Panel, Sound and Audio Devices icon, Hardware tab, Properties dialogs. There will be a list of driver files. If you see "wmk" or "asio" you should be OK in the latency department. You can also google on the driver name and may be able to find out more that way.

Of course you can also hook up Csound and a MIDI keyboard and just try playing all the drivers in turn. You will soon be able to tell what the story is. You also need to adjust your Csound options according to recommendations in the manual for live performance.

In addition, the interface built into the computer, i.e. the headphone jack, which may or may not come with a kernel mode driver, is likely in any case to be noisy, distorted, and/or have an inadequate frequency response; you really should get an external interface. These almost all come with kernel mode or ASIO drivers and have gotten both small and inexpensive. An example (this is not a recommendation, just an example) is the Tascam US 122 L.

Hope this helps,
Mike



-----Original Message-----
>From: Felipe Sateler 
>Sent: May 9, 2008 1:09 PM
>To: csound@lists.bath.ac.uk
>Subject: [Csnd] Finding out where latency is
>
>I have a laptop which I'd like to use as a mobile synth-effects processor. 
>However the latency it has for realtime operations is too much for it to be 
>used effectively. How can I find out where the latency is, to see if it is 
>fixable? I mean: if I can somehow determine that the latency is in the 
>soundcard, then I can buy a new one and solve the problem. OTOH, if the 
>latency is in the PCI bus, then I don't have much to do other than buy a new 
>laptop.
>
>A simple instrument in csound like this
>instr 1
>	asig in
>	out asig
>endin
>
>still has some latency.
>
>-- 
>Felipe Sateler