[_euac]

I had the same issue with LibreOffice choking with big datasets so I've started using SoftMaker PlanMaker for loading anything with more than a few hundred records. It's works just fine with documents with tens of thousands of rows and it allows me to do the - admittedly very simple - calculations and charting I need.

The whole SoftMaker Office suite is pretty nice. Not sure where it's on feature parity with Microsoft Office, but the price isn't terrible (something like $20 a year for the paid version, or free if you don't care about the paid features) and it does a great job of reading Office files.