Last Thursday I was happily walking to the bus station to start a prolonged weekend when a friend and client rang. Microsoft Excel was giving her trouble: she was working on some inventory files with lots of records and pretty complex. To add to the problem the data was copied and pasted from an online list inside the browser. I suspect that some junk from the web inventory list tagged along.
Not being able to see the problem first hand I made the only recommendation that I could do over the phone: give open office a try.
To make a long story short it worked. The performance she got from OpenOffice Calc was way better.
So if you are having performance and speed issues with Microsoft Excel give Open Office a spin. It might be a lot of help.
You can find it here.