Can't say why (yet), but I can confirm your findings on 5.8.6 under XP.
c:\test>junk6
Section A took 1.0150 CPU seconds
Section B took 3.3750 CPU seconds
Section A took 1.0150 CPU seconds
Section B took 5.1410 CPU seconds
c:\test>junk6
Section A took 1.0310 CPU seconds
Section B took 3.4540 CPU seconds
Section A took 1.0000 CPU seconds
Section B took 5.0780 CPU seconds
:\test>junk6
Section A took 1.0470 CPU seconds
Section B took 3.5470 CPU seconds
Section A took 0.9690 CPU seconds
Section B took 4.8910 CPU seconds
c:\test>junk6
Section A took 1.0310 CPU seconds
Section B took 3.4690 CPU seconds
Section A took 1.0160 CPU seconds
Section B took 5.1560 CPU seconds
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.