Excel freezing/slow/ taking up 99% CPU

[Questionz]

I'm working on a sorta large excel file. It's only about 5MB. When I have to do anything simple, it takes a loong time. the program greys out and says (not responding). Eventually, it finishes but not at a practical rate to be functional for me....I have an i5 processor, 6GB RAM ASUS laptop. Windows 10...

Disk and CPU are soaring at 100% and my computer fan rages....I have no clue what's going on.

problem is, I need to make the file bigger but I can't even do basic functions already without freezing. I opened the same document on another computer and though it took a while to open initially, it seemed to function OK. I was initially using the 2013 edition and i uninstalled it and tried 2016...no difference. I did a bunch of virus scans, defragged my computer, did clean up, etc...no difference.

I tried it in a freeware program LibreOffice Calc (that's their awkward version of excel) and the document didn't seem to have as many problems. It was slightly slow but it was functional.

Does this just sound like my computer (hard to imagine since the specs are decent) or is there anything I can do for excel to stop using up so much resources??? Very frustrating...

any thoughts are appreciated.