From The Labs: 64-bit beta 2 in News Posted March 15, 2013 · Report reply Hi! I'm glad 64-bit will be supported, as most of my programs require it. However, I just tried the 64-bit beta 2 using 8GB of RAM, and it works - generating all the correct output - but runs way slower. Oracle's 1.6 javac.exe and java.exe: Loaded Reference: 3.306 seconds. Generated Index: 3.049 seconds. Analyzed Index: 4.156 seconds. Mapping: 39.733 seconds. JET 64-bit beta2: Loaded Reference: 12.045 seconds. Generated Index: 46.464 seconds. Analyzed Index: 21.322 seconds. Mapping: 272.439 seconds. Particularly the phase "Generated Index" is very odd; this is basically just reading serialized int arrays, which java.exe can do at over 500 MB/s (since Windows 7 caches the files in memory) but JET mysteriously reads at about 50 MB/s. The mapping phase is multithreaded, using 7 threads on an 8-thread hyperthreaded CPU, and both executions indicate 7 threads are being fully used... but it's still slow. Is speed a known issue in the beta, or is my program an anomalous use-case?