Profiling and Optimization

From BlackBerryDev

The content on this page is a compilation of various tips and tricks learned from DevCon presentations and personal experiences. It should be expanded upon and organized as appropriate.

Profiling and optimization

• Optimization tricks that would be counterproductive in J2SE actually do help a lot on the BlackBerry JVM
• Math, networking, persistence, file I/O, and compression have substantial and disproportionate performance differences between the simulator and the real device
  • Network I/O latency can be quite substantial, especially the lag when opening a fresh socket connection.
  • The biggest bottleneck with file I/O appears to be opening and closing files, not actually reading/writing data.
• Consider compressing all persistent/file data, since reducing I/O helps performance a lot, and the zlib implementation in the API is actually pretty fast
• 5.0+ can detect a process leak on the simulator
• Look for "ApplicationRegistryHashtable" in the debugger when trying to trace an application reference
• 4.5+ supports on-device profiling

Optimizing image data

• JPEG
  • Remove metadata
  • Quality settings can sometimes go as low as 20-30% without the user noticing
• PNG
  • Use less than 256 colors, PNG8 format
  • Use the "565" color-space if possible (this is the device color-space)
  • The BlackBerry theme development tools can export 565 and PNG8
• Runtime memory cost of images:
  • Opaque: 2 x W x H / 1024 = KB
  • Semi-transparent: 3 x W x H / 1024 = KB
  • Use padding and margins instead of empty bitmap space, and crop icons closely

• Don't pre-composite images