Hands-On High Performance Programming with Qt 5

General performance optimization approach

Up to now, we listed the following classic optimization techniques:

• Optimal algorithms
• Optimal data structures
• Caching
• Precomputed tables
• Preallocation and custom allocators
• Buffering and batching
• Read-ahead
• Copy avoidance
• Finding a better library

With our current stand of knowledge, we can formulate the following general-performance optimization procedure:

1. Write your code, avoiding unnecessary pessimizations where it doesn't cost much, as in the following examples:
   • Pass parameters by reference.
   • Use reasonably good, widely known algorithms and data structures.
   • Avoid copying data and unnecessary allocations.

This alone should give you a pretty decent baseline performance.

2. Measure the performance, ...