Runs on the old box

No positional information and O_STREAMING, reuse btree object, no fdatasync, "dangerous" patch applied, mounted noatime, pack_uint_preserving_sort:

No positional information and O_STREAMING, reuse btree object, no fdatasync, "dangerous" patch applied, mounted noatime:

No positional information and O_STREAMING, reuse btree object, no fdatasync, "dangerous" patch applied:

No positional information and O_STREAMING, reuse btree object, no fdatasync:

No positional information and O_STREAMING, reuse btree object:

No positional information and O_STREAMING, no fdatasync (slowed at start by checksecurity cronjob):

No positional information and O_STREAMING:

With O_STREAMING on article reads (accidentally run on a subsection of the spool so the data being indexed is different and this graph can't really be compared to the others):
Original run: