The compile-time options you choose can greatly improve the performance of the code generated by the compiler. However, like most performance considerations, there are trade-offs associated with these choices. Fortunately, you can weigh the trade-offs associated with compile-time options without editing your source code because these options can be specified on the command line or in the environment variable IBM.OPTIONS.
If you want to avoid details, the least complex way to improve the performance of generated code is to specify the following (non-default) compile-time options:
The first two options can affect the semantics of your program, but generally only do so in unusual situations. If you specify the first two options, your code is improved even when compiled with optimization turned off. By using these options, the compiler is also less likely to make errors.
The following sections describe, in more detail, performance improvements and trade-offs associated with specific compile-time options.