What do you call "slow"? One minute to start? 10 minutes?
Also it depends on your computer, although I suppose that if you still run XP on it, it shouldn't be recent / powerful.
Also, you are talking about the time to run the PDE, or to run a sketch?
I found out that even on a modern computer, a sketch in 2.0 can be rather slow to start (10 to 30 s on a recent computer, particularly if using anything but JAVA2D).

When I start Processing the first time after a reboot, it takes about 20 seconds to load the IDE. If I close Processing and restart it, then it takes 2-3 seconds to reload.

In my main PC, a Q6600 2400MHz CPU model using WinXP (32-bit) and recognizable 3.5 GB of RAM, Processing (1.5.1) starts and runs reasonably fast.
I use latest JDK 6 series (removed Processing's one) and no active malware protection (just passive ones).

Tip: Use CCleaner to remove useless files and registers which clog your OS -> CCleaner

i just timed it and it was well over a minute for the application to load.