When I use mobile phones to access campaign spreadsheets, I usually run into the same problem. It takes longer to load and display all information in the spreadsheet. I have the Google Sheets App installed on my phone, but I still have the same problem, though not with all spreadsheets, just a few of them. I haven't tried opening those spreadsheets on a PC yet; perhaps it will be much easier to do so there.
It's because your phone has limited hardware, and your computer is both faster in terms of CPU speed, and likely RAM. Unless, you have a particularly limited computer, that is. Loading spreadsheets with more data will take a lot more resources.