There are a range of techniques for maximizing the performance of your COBOL programs. As a general rule, the simpler the operation, the faster it executes and the smaller the compiled code.
There are a number of optimizations that you can take advantage of without being required to make extensive changes to your source code. A number of compiler directives are available that apply low-level optimizations as part of the compilation process. Most directives focus on optimizing specific facets of your code, and so you should check that they are suitable for your application before applying; but there are other directives, such as OPT, that offer performance gains that should be considered for most applications.
The following optimizations refer to native COBOL applications; for JVM COBOL applications different considerations apply.