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Java Performance Tuning: Optimizing the Performance of Java Applications

Published On: May 12, 2023

Java has been a programming language for more than 20 years. Java’s performance was initially inadequate compared to other modern languages as it relies on the Java Virtual Machine (JVM) and garbage collection methods.  But since then, in part because of numerous changes in recent releases, its performance has increased. Join SLA for the Best Java Training in Chennai with Best Practices.

JVM’s performance has undergone significant optimization. In this article, we are explaining how to optimize the performance of Java Applications using Java Performance Tuning. 

Table of Contents

  1. What is Performance Tuning
  2. Top 10 Tips for Performance Tuning 
  3. Upgrading to the latest Java version
  4. Avoiding writing long methods
  5. Sizing the Java heap memory properly
  6. Choosing the Appropriate Garbage Collection Algorithm
  7. Using Profiler to find the real bottleneck
  8. Prioritize the biggest bottleneck first
  9. Using StringBuilder to Concatenate Strings Programmatically
  10. Avoiding Multiple If-else statements
  11. Using Stored Procedures instead of queries
  12. Ensuring the thread pool of Web Container is measured correctly

What is Performance Tuning?

Whatever language or platform you use, it may be difficult to write apps that perform well, and Java is no exception. In addition to the usual issues, Java performance optimization has its own inherent difficulties. Consider the two-edged sword of rubbish collection as an example.

That doesn’t mean that you can’t optimize your apps or that you need to be an expert to do so. You may make an effective application by following some simple best practices and guidelines.

Top 10 Tips for Performance Tuning

Here are the top 10 tips to help you optimize the performance of your Java Applications. Read through our article that provides 15 tips about our Java Training offered by SLA.

1. Upgrading to the Latest Java Version

Performance has improved with each new Java release. To benefit from these performance enhancements, make sure to use Java’s most recent stable release. For instance, benchmarks show that utilizing Java 18 over Java 15 results in a 5–16% performance gain.

New constructs have also been included in more recent Java versions to alleviate some of the problems with earlier Java versions. You can experience significant performance advantages by using these more recent constructions. For instance, concurrentHashMap, which was added to JDK 1.5, performs better than the more common Hashtable data structure.

It is advised to upgrade to the most recent stable release if security is also a concern. For instance, TLS v1.2 is used as the default transport-level security standard for HTTP connections that are SSL-based. As a result, if you utilize a JVM version older than 1.1, your application may be vulnerable to security risks associated with TLS v1.1.

2. Avoiding Writing Long Methods

The approaches employed ought to be succinct and concentrated on a specific aspect. Since the method is loaded in stack memory during class loading and method calls, it is better for maintenance and performance. Memory and CPU usage increase during the execution of techniques when they are overly complex and need a lot of processing time. At appropriate logical intersections, try to split the methods into smaller ones.

Avoiding designing lengthy methods is one of the simplest ways a developer may increase Java performance. Long methods will take longer to execute on your Java Virtual Machine. The main function in your program is called the JVM, which is a component of the Java Runtime Environment (JRE). The JVM, also known as the Java Virtual Machine, is in charge of creating an environment in which Java programs can be executed. 

This enables Java applications to operate on any machine or operating system. If your application’s methods are short and to the point, they won’t cause it to lag. This is so that you may minimize the amount of processing required and lower CPU usage by keeping your methods brief. In order to maximize processing performance, programmers can divide a huge method into numerous methods at appropriate logical locations.

Based on prior interpreter mode executions, the Just-in-Time (JIT) compiler identifies the optimizations required to turn a method into native code. This results in code that runs more quickly and efficiently. Your procedure won’t be JIT compiled by the JVM if it is lengthy, and it is also less likely to be inlined. On the other hand, if your method is short, JVM inlining and JIT compilation work best with it.

Check out this popular tweet about Java Performance Tuning. It provides a complete guide about optimizing the performance of Java Applications efficiently.

3. Sizing the Java Heap Memory Properly

Although the JVM does manage memory dynamically, it still has to be set up with enough memory to function. Common signs that you might not have appropriately set up your RAM include:

  • When you first launch your application, everything is OK, but as time passes, it gets slower and slower. A restart usually resolves the problem.
  • When running your program, java.lang.OutOfMemoryError errors start appearing. This error is typically generated when the JVM runs out of memory and is unable to allocate an object because the garbage collector has exhausted all available memory.
  • The GC process consumes a significant amount of CPU cycles and garbage collections occur frequently.

The JVM’s memory configuration is set when the Java application initially launches, and it cannot be altered dynamically. Any modifications to a JVM’s memory configuration must be applied after restarting the program.

The maximum amount of heap memory you can give the application is controlled by the Xmx JVM parameter. This JVM argument is arguably the most significant. A Java application’s heap size needs to be set optimally. Setting a heap size that is too small will lead to out-of-memory problems, which will prevent your application from running correctly until it is restarted. 

The Performance will be negatively impacted by setting an extremely big heap memory. Less often occurring garbage collection may free a significant amount of RAM when it does. This can cause pauses in the application.

Memory shortage could also result from memory leaks in the application; to identify memory leaks, take a heap dump and analyze the memory used by various objects using a tool like the Eclipse Memory Analyzer Tooling (MAT). Make sure to keep an eye on the heap usage of your JVM; if the heap usage ever approaches 90%, it shows that you will need to tune the memory accessible to the JVM.

4. Choosing the Appropriate Garbage Collection Algorithm

Modern JVMs offer a variety of garbage collection algorithm options.  For JDK 12 and newer, these are a few trash collection options:

  • Serial GC
  • Parallel GC
  • Concurrent Mark and Sweep GC
  • G1 GC
  • Shenandoah GC
  • Z GC
  • Epsilon GC

When starting your program, if you don’t specifically specify the GC algorithm, JVM will use the default algorithm. The default GC mechanism was Parallel GC before Java 8. G1 GC has been the standard GC algorithm since Java 9.

The performance of an application can be significantly influenced by the GC algorithm selection. For instance, it is said that G1 GC and Z GC perform significantly better than Concurrent Mark and Sweep GC. It should be noted that ZGC is accessible on Linux starting with JDK 11 and on Windows starting with JDK 14 (Windows 10 or Windows Server 2019 are prerequisites). You must give the JVM the -XX:+UseG1GC argument to use G1GC.

5. Using Profiler to Find the Real Bottleneck

Where should you start after following the first suggestion and identifying the areas of your application that want improvement?

This issue can be approached in one of two ways:

  • You can glance over your code and start with the section that seems odd or where you think it might cause issues.
  • Alternatively, you can use a profiler to obtain comprehensive data regarding the operation and behavior of each component of your code.

It should be clear that the profiler-based approach enables you to concentrate on the most important sections of your code and provides you with an improved awareness of the performance implications of your code.

And if you’ve ever used a profiler, you probably recall a few examples in which you were taken away by the specific areas of your code that were to blame for the performance issues. 

“We encounter the concept of optimization while working on any Java application. The code we write must be not only clear and error-free but also optimized, meaning that the amount of time it takes to run should be within the predetermined range. To achieve this, we must refer to the Java coding guidelines and make sure our code compiles. “

6. Prioritize the Biggest Bottleneck First

You also have a list of issues you wish to solve to boost performance after creating your test suite and using a profiler to analyze your application.

That’s great, but it still doesn’t address the issue of where to begin. You might start with the most pressing issue or concentrate on the fast wins.

Given that you will quickly be able to demonstrate initial outcomes, it may be tempting to start with the quick wins. In some cases, you might need to do that to persuade your management or other team members that the performance analysis was worthwhile.

However, in general, we advise starting at the top and tackling the biggest performance issue first. That will give you the biggest performance boost, and you might only need to address a couple of these problems to meet your performance needs.

7. Using StringBuilder to Concatenate Strings Programmatically

In Java, there are several different ways to concatenate Strings. For instance, you could use the simple + or +=, the trusted StringBuffer, or a StringBuilder.

So, which strategy should you favor?

The solution will depend on the code that was used to concatenate the String. Use the StringBuilder if you’re adding new data to your String programmatically, like in a for-loop.

Although it works better than StringBuffer and is simpler to use, StringBuilder is not thread-safe, unlike StringBuffer, and therefore may not be appropriate in all circumstances.

To add a new component to the String, you just need to execute the append method on a new instance of the StringBuilder. And once all the pieces have been combined, you can use the toString() method to get the combined String.

An easy example is shown in the following line of code. This loop turns ‘i’ into a String and adds it plus a space to the StringBuilder sb at each iteration. Therefore, this code ends by writing “This is a test0 1 2 3 4 5 6 7 8 9” to the log file.

StringBuilder testsb = new StringBuilder(“This is a teststringbuilder”);

for (int i=0; i<10; i++) {


sb.append(” “);


The constructor method can accept the initial element of your String, as shown in the code example. By doing so, a new StringBuilder will be created with the provided String and 16 more characters available. Your JVM will dynamically expand the StringBuilder’s size as you add additional characters to it.

If you already know how many characters your String will have, you can pass that information to various constructor methods to instantly create a StringBuilder with the specified capacity. 

As a result, it becomes even more efficient because it no longer needs to dynamically increase its capacity.

Java at Microsoft

8. Avoiding Multiple If-else statements

Our code makes decisions using conditional statements. Avoid using conditional statements excessively. The performance will be impacted if we use too many conditional if-else statements since JVM will need to compare the conditions. If the same is used in looping statements like for, while, etc., this could get worse. 

If your business logic contains too many criteria, try grouping them to provide a boolean result that can be used in the if statement. Additionally, if possible, we can consider substituting a switch statement for several if-else statements. Performance-wise, switch statements outperform if-else statements. 

As an example of what to avoid, the following sample is offered below:

if (condition1) {

    if (condition2) {

        if (condition3 || condition4) { execute ..}

        else { execute..}

Avoid using the example above and instead use the following:

boolean result = (condition1 && condition2) && (condition3  || condition4)  

9. Using Stored Procedures instead of Queries

Instead of writing intricate and lengthy queries, it is preferable to build stored procedures and use them when processing. Pre-compiled stored procedures are kept in the database as objects. As a query is built and run each time it is called through the application, the execution time of a stored procedure is faster than a query with the same business logic. The stored procedure also reduces data transfer and network traffic because the database server does not need to be transferred with each execution of the complex query.

10. Ensuring the Thread Pool of Web Container is Measured Correctly

Even with the most efficient code, if the web container is not configured properly, your application will not run as expected. There are restrictions on the number of threads that can be launched when web containers like Tomcat, JBoss, WebLogic, and WebSphere process requests. For the majority of production workloads, these containers’ default settings are extremely low. Check your web container’s thread pool configuration to make sure no inbound requests are being held up while waiting for threads to become available to process them.

Java - Thread Pool of Web

While it’s crucial to make sure your web container has enough configured threads, it will also be bad to set the thread pool size to an excessively high value. Excessive context switching results from the JVM having to manage too many threads. Additionally, garbage collection can be triggered more frequently, which would hurt the application’s overall speed. So keep in mind that when it comes to Java thread pools, more isn’t necessarily better!


Application developers are not solely accountable for an application’s performance. Application operations teams must play a significant part in ensuring the availability and high performance of their production applications. We’ve looked at 10 alternative configurations in this blog post that application operations teams can tweak to improve the speed of their Java online apps.

To evaluate and enhance the performance of Java apps, use load testing tools and Application Performance Management (APM) solutions. While it is essential to perform load testing for various application situations, you should also keep an eye on the CPU, IO, and heap memory at the same time.

For more tips and technologies, enroll in our Best Java Training in Chennai and get hands-on exposure to Performance Tuning for Java Applications.

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