Greetings

I have a spreadsheet that is 70 columns wide by 2604 rows tall where I input daily production data. There are 8 index/match lookups to pull data from an external excel file, and several internal formulas doing various calculations, but nothing out of the ordinary. The index matches only extend to row 580 as I have done a copy/paste special - values in order reduce the amount of file overhead being used.

Intermittently my spreadsheet will stop responding as it should, lagging between cursor moves and such. The triangles in the corner of the cells containing formulas that aren't protected take approximately 1-2 seconds EACH to show up when normally this is near instantaneous. I have checked below my data to make sure that no formulas have inadvertently strayed below the main area of data. I have a colleague who uses the same file and has no problem with it. I have gotten a brand new pc and a brand new software install and I still have the problem.

Does anyone have any idea what could be causing it?

Thanks