According to Blast results: jfxsrc.us.oracle.com//sandbox/javafx/presidio/blast/presentations/Blast1.pdf using floats for vertex data is expensive both in terms of RAM usage and GPU performance - consider using short/byte where appropriate.

As long as the data can be normalized, it can be compressed from floats to short/byte, unless the range requirement is enormous (ie. Prism drawing to screen resolution windows should fit the requirements for vertex compression).

Attaching the relevant slide from the Blast1 presentation.