Thanks for joining us on our community forum!
I'm sorry to read you're facing performances issues accessing a spreadsheet document. Can you tell us where did that happen? Are you using our flagship instance cryptpad.fr? Another one?
Do you have a good internet connection? Can you do a quick speedtest for us and share the results here?
Also, I'd like to know what device are you using to access the spreadsheet. Is it a computer, a smartphone? What brand and model? Do you know its specifications (mainly what processor & the amount of virtual memory available)?
Thanks in advance for your answer!