How to run 32-bit Java on Mac OSX 10.7 Lion

Question

From my experience with Windows 7 (64-bit) and Java, a 32-bit JRE uses less memory and runs significantly faster than a 64-bit JRE (provided you don\'t need or benefit from

Answer 1

The latest versions of Java 64-bit have -XX:+UseCompressedOops on by default (if your heap is less than 32 GB). This means 32-bit references are used in any case. The objects are still slightly bigger (4 bytes more overhead)

This article compares 32-bit, 64-bit with UseCompressedOops Java: How much memory do different arrays and collections consume

In terms of performance, I have found it to be 5-10% depending on what you are doing. If you are using a lot of long values it will be faster to use 64-bit.