I know this isn't the answer you're looking for, but your problem
description sounds like the classic case of trying to make Excel behave like
a database. It will do this up to a point, but it sounds like you're well
past that point.

If you have Access and can spend some time learning SQL you could export
both tables into Access, extract the non-duplicate rows from the first table
and load them back into Excel with zero programming and probably not more
than a few seconds of CPU time.

--
Rob Bovey, MCSE, MCSD, Excel MVP
Application Professionals
http://www.appspro.com/

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"Spammastergrand" wrote in message
...
I'm having a big problem in Excel XP. I'm trying to write macros that
compare
2500 rows in one sheet to 27,000 in another to see if there are
duplicates.
I've tried loops, finds, even filters. The problem is its maxing the
computers
resources with CPU usage going to 100% in Task Manager. In fact it
freezes,
saying, Not responding, when looking at the process in Task Manager.

Even without programming this happens when I try to filter certain fields.
Anyone have any ideas? If the machine cant run the comparisions without
locking
up people will have to manually check new data against 27,000 pre existing
rows
to see if they are duplicates, updates, or new.

Also when I do a find, does looking in formulas intead of values speed it
up?