Pro Android Apps Performance Optimization

Accessing Memory

As we saw earlier, manipulating larger types can be more costly because of the higher number of instructions involved. Intuitively, more instructions often result in lower performance simply because of the extra work the CPU has to perform to execute them. In addition to that, code and data both reside in memory, and accessing memory itself has a cost.

Because accessing memory is a costly operation, a CPU caches the memory that was recently accessed, whether it was memory that was read from or memory that was written to. In fact, a CPU typically uses two caches organized in a hierarchy:

• Level 1 cache (L1)
• Level 2 cache (L2)

The L1 cache is the faster but also the smaller of the two. For example, the L1 cache could be 64 kilobytes ...