With 64 Bit Java JPT can use a larger maximum amount of RAM through the
startup parameter "-Xmx". Usually this is not necessary, but if you have
many images in an folder or search result or JPT renders thumbnails of
huge images (more than 100 MB), this may improve speed.
I'm using "-Xmx1g" - 1 Gigabyte even under 64 GB Windows/Linux and that
is also possible with 32 Bit Java. My RAW files' sizes up to 16 MB and
16 Bit TIFFs up to 80 MB. "-Xmx2g" is not possible with 32 Bit Java -
tested under Windows with 16 GB RAM - 32 Bit programs can use only about
If you let create thumbnails with an external 64 Bit program, 64 Bit
Java is required, also if you use scripts calling 64 Bit programs. I
didn't test that, but if your scripts using 32 Bit programs that can be
a problem with 64 Bit Java.