Always enabled, as this runs for me with an overhead in the range of
measurement error (in tail_build):

current implementation: time make -nsrj8
17.269s 16.470s 17.537s 16.754s 16.595s

disabled: time make -nsrj8 gb_CHECKOBJECTOWNER=
13.212s 13.345s 13.470s 13.852s 13.712s

new implementation: time make -nsrj8 gb_CHECKOBJECTOWNER=
13.477s 13.911s 13.624s 13.606s 13.535s