A Gallardo is not a fair benchmark to choose. I've had a play with one in WUF.
When I first got my 944S back on 1990 it felt agile but not fast. Certainly not much faster than the 944 Lux I had 6 years earlier. I have to say it now feels a lot more agile after wheel / tyre / suspension / brakes uprates.
However, it doesn't feel faster. This is almost definately because it's about 30 BHP down on factory figures. This looks to be due to valve guides and has been confirmed as a typical symptom of a 944S with over 100,000 miles. Over the winter, the head will come off and be rebuilt with new guides etc to prove it one way or the other.
Modification wise, it has an ESS rear exhaust section, Cone air filter and A Blitz chip. The first two made virtually no difference. The chip did make a good difference to the power and cost an extremely reasonable £50 or thereabouts. The fuelling is not particularly good, though.
Interesting that the car attracts an inflated insurance premium because of the mods, but is proved to currently produce only 175 BHP against a claimed factory standard power of 192 BHP - that's still 17 BHP down from standard .... I'd certainly get any newly purchased 944S checked on a dyno to see how down on power it is.
But firstly and most importantly as mentioned above, get the cam chain and tensioner and probably belts changed by a specialist as soon as possible. These things are a real potential weakness on this engine unless properly serviced and looked after and you REALLY don't want to know how much it'll cost you to replace a head on a 944S (good ones are like rocking-horse poo), or bent valves etc.
So ultimately to recap ... no, against a supercar it will feel like a milk float. The engine doesn't have a lot of torque and relies on it's extended 6,800 RPM redline to really get shifting - making it harder work than an S2, or even LUX.
That said, it is an extremely enjoyable car to drive - much more so than my WRX-RA which would leave it for dead in a traffic light grand prix, but on a reasonable journey involving A and B roads, you would probably arrive about the same time, much more relaxed, MUCH more economically and above all, still with a smile on your face in the 944S.
HTH
Rick.