Simple Java performance tuning tips

  • To start optimizing your app, use a profiler to find the real bottlenecks in the code and then create a performance test suite for the whole application based on that information. Run your tests before and after every attempt at optimization.
  • Use primitive types rather than wrapper classes wherever possible to minimize overheads as they are stored to the stack and not the heap. Avoid BigInteger and BigDecimal as they dramatically slow down calculations and use a lot of memory.
  • If your app uses a lot of replace operations and you aren’t updated to the latest version of Java, consider the Apache Commons StringUtils.replace method rather than String.replace. You can make the change easily by adding a Maven dependency for Apache’s Commons Lang to your app’s pom.xml to replace all instances.
  • Cache especially your more expensive resources or most-used snippets of code, such as database connections or the valueOf method for the Integer class. However, you are creating an overhead and you may need to manage the cache to keep it accessible and remove outdated information, so be sure the tradeoff is worthwhile.

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