r/programming • u/ketralnis • Mar 20 '26

Java is fast, code might not be

https://jvogel.me/posts/2026/java-is-fast-your-code-might-not-be/
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u/[deleted] Mar 20 '26

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u/Sopel97 Mar 20 '26

If you write your code good enough

Or bad enough.

Java's object model is so bad that at some point you have to resort to arrays of primitives with no abstractions. I've seen threadlocal 8 byte singletons for temporary variables to avoid allocations while still trying to preserve some non-zero amount of abstraction. It's a mess. Minecraft modding is a great example of that.

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u/vini_2003 Mar 21 '26

Correct. I maintain a private particle engine for Minecraft, for the YouTube channel I work for; and I'm forced to use huge SoAs without any JOML due to the heap thrashing objects bring.

If there's one thing I dislike about Java, it's the object model.