What are the optional Sun Performance Library and J2SE downloads listed on the Sun Studio 10 download page?
Sun Performance Library(tm) is a collection of highly optimized mathematical subroutines for solving linear algebra and other numerically intensive problems. If you are creating high performance applications that require this functionality, be sure to download and install this package (available for the Solaris OS only). The J2SE(tm) Platform file includes the J2SE 1.4.2_06 technology needed to run the graphical Integrated Development Environment (IDE), including the graphical debugger and application Performance Analyzer. Without it, the IDE MAY fail upon startup if it cannot locate an appropriate version of the J2SE technology. This file is not needed to run command line tools.