In addition to fixes, the 6.3.0 SP2 maintenance release includes a number of new OS-kernel features:

• SH4A Processor Support
• Mutex optimization on SH4 and ARM
  • Up to 3x faster for uncontested mutexes
• Improved malloc
  • Speed improvements for small allocations
  • Reduced contention in highly-threaded apps
• Debug malloc enhancements
  • Memory leak detection
  • Deep stack traces