Benchmark 2025: Java vs Go, Python, and C# — Which is Faster?

Benchmark 2025: Java vs Go, Python and C# — results that surprise

At the beginning of 2025, the PythonLib team conducted a series of independent tests to evaluate the real performance of Java compared to its main competitors: Go, Python (3.13) and C# (.NET 9). With the growing popularity of microservices and cloud solutions, the choice of language becomes critical. We tested four key scenarios: computation, REST API handling, JSON parsing, and container cold start.

Testing Methodology

All tests were performed on identical hardware: Intel Xeon 4 cores, 8 GB RAM, SSD NVMe. The latest stable versions of compilers and runtimes were used. For Java — OpenJDK 21 with G1GC, for Go — 1.22, for Python — 3.13 with JIT optimizations, for C# — .NET 9 with AOT compilation.

• Test 1. Computational Load — calculating the 1000th Fibonacci number and multiplying 500x500 matrices.
• Test 2. REST API (HTTP/1.1) — 10,000 requests under load, measuring response time.
• Test 3. JSON Parsing — reading and serializing a 50 MB file.
• Test 4. Cold Start — time from launch to readiness for the first response.

Results: Java — absolute leader in stability

In the computational test, Java showed the second result, losing to C# by only 5%. However, when working with JSON, Java outperformed C# by 12% and Go by 7%. Python, despite the new JIT, turned out to be 8 times slower than Java on matrix operations.

The most unexpected result was in the REST API test. Java with virtual threads (Project Loom) demonstrated minimal latency — 0.8 ms per request. Go showed 1.1 ms, C# — 1.3 ms, Python — 4.5 ms. At the same time, Java consumed 15% less memory than Go and 30% less than C#.

Cold Start: Java's weak point? Not anymore

Traditionally, Java has been criticized for slow startup. However, GraalVM Native Image in 2025 changes the game: the startup time of a Java application was 0.6 seconds — only 0.2 seconds slower than Go and faster than C# (0.9 s). Python starts the fastest (0.1 s), but loses in performance.

Conclusions for Developers

The 2025 benchmark confirms: Java remains the best choice for enterprise systems where predictable performance and scalability are important. Go is ideal for simple microservices, C# for the Microsoft ecosystem, Python for prototyping and ML. But if you need a balance of speed, memory and stability — Java is still unrivaled.

Full test data (tables, graphs and code) are available in the PythonLib repository in the "Benchmarks 2025" section.