I'm not sure whether this is an OS issue, hardware or a combination of both but.... I am running a macro to calculate and analyse stock data, involving a large number of large files and a complete run can take anywhere between 12-36 hours ( I understand there may be better solutions but I just stick with what I know....). I started with just one PC, an intel i7, however to speed things up, I started running on a second computer, an older Core 2Duo. (Same macro, different stocks) Now I assumed, that my newer i7 would get through the macro a lot quicker, however after running them side by side, I have found that the Core 2Duo is getting through the macro at least twice as fast as the i7( Itested using the same files on both to check). Is someone able to offer a reason for this huge gap in performance? Below are the basic specs for both pcs. Is older CPU better designed to handle this sort of work? Or something to do with the difference in OS? Intel Core 2Duo E8500 @ 3.16 , 4gb memory , 256gb SSD, OS - XP, 2010 office Intel i7 960 @3.2 ,6 gb memory, 256gb SSD, OS - Win 7, 2010 office Thanks in advance!