i've found out that 8.7i use less resources than 8.5i.
just installed it at celeron 1,8 Ghz (400 fsb) with 512mb of ram and 64mb graphic adapter (yes! very old model of computer) and it run smoothly, not like the 8.5i (with patch 6). is it because the 8.5i's patch that pretty old or because the new engine that makes the 8.7i feel 'faster'? i dont really know.
im using xp sp3 as operating system.