Look up "data oriented design" GDC talks or "AoS and SoA" for more in depth information to your question. The very brief tldr is that if you want to go fast, yo

Look up "data oriented design" GDC talks or "AoS and SoA" for more in depth information to your question. The very brief tldr is that if you want to go fast, you have to design for cache locality and memory access patterns. In particular for Java there's regularly dependent pointer loads, which are dreadfully slow on modern CPUs and also waste a significant amount of L1/L2 cache.