I don't think the 100M entries example suffers from inlining or profile pollution. It's just that the manual loop is going to be as tight as you can get it and

I don't think the 100M entries example suffers from inlining or profile pollution. It's just that the manual loop is going to be as tight as you can get it and it's likely the stream version leaves artifacts behind that are noticeable when the loop kernel is dead simple like this. -XX:UnlockDiagnosticVMOptions -XX:+PrintInlining will tell you whether this inlined, and dumping the JIT asm can be done to see what was actually generated.