After 4 1/2 years it was time to send my old laptop into retirement. A replacement laptop with a 512 Gig SSD Samsung PM830 did the trick. Old laptop was freshly defragmented XP 32 bit 2 gig ram dual core 2.2 GHz cpu. New had Win 7 64 bit, 16 gig, 512 SSD quad core i7 2.5 GHz.
Building my system both with a 32 bit JDK with ProGuard obfuscating turned on "Clean and Build all":
OLD system: 4' 25 sec
NEW system: 1' 29 sec
Launching NetBeans (6.5) with around 50 modules:
OLD system: 25 sec
NEW system: 8 sec
In general a 3x increase in speed ! I strongly believe the disk I/O is the major consumption of time here. CPU and Memory is only contributing minor.