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GC pressure is another factor. Even in the trivial ownership case, gc:ing in a GB/s allocation environment comes at a cost.

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Adding Guava testlib's GcFinalization.awaitFullGc() before a benchmark run and -XX:+UseParallelGC, I saw the runtimes decrease by 30s in Bench_Fury_Ordinal and 20s in Bench_ObjectOutputStream. Ideally you would run using JMH to avoid jit warmup issues, previous runs, etc from polluting your results.

Did you dial up to run for 1 billion items?

In general I'm not a big fan of JMH for testing sustained I/O scenarios, as CPU, OS and storage behavior are extremely relevant, and JMH tends to interfere with access patterns.

Nope, I used the default in your github repository (10_000_000). From a quick profile it looked like previous benchmark allocations where crossing into later runs, who were then penalized unfairly, so I made those small adjustments.

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