Another person having the same issue: https://ask.libreoffice.org/en/question/195056/calc-incredibly-slow-to-load-and-save-large-but-simple-ods/ The end result is huge, slow-working files.
Thank you for reporting the bug. Please attach a sample document, as this makes it easier for us to verify the bug. (Please note that the attachment will be public, remove any sensitive information before attaching it. See https://wiki.documentfoundation.org/QA/FAQ#How_can_I_eliminate_confidential_data_from_a_sample_document.3F for help on how to do so.) I have set the bug's status to 'NEEDINFO'. Please change it back to 'UNCONFIRMED' once the requested document is provided.
Created attachment 155316 [details] An example spreadsheet that is extremely bulky and slow.
You did not qualify in any way this slowness, but in your AskLibO question you said the time to open is 20 minutes for you. In the AskLibO thread you also mention using version 6.2.3. For me, opening attachment 155316 [details] takes 22 seconds. Could you please test with version 6.4.x? Set to NEEDINFO. Change back to UNCONFIRMED, if the problem persists. Change to RESOLVED WORKSFORME, if the problem went away. Arch Linux 64-bit Version: 6.4.3.2 Build ID: 6.4.3-1 CPU threads: 8; OS: Linux 5.6; UI render: default; VCL: kf5; Locale: fi-FI (fi_FI.UTF-8); UI-Language: en-US Calc: threaded
That was someone else in the AskLibO, but yes, I'm no longer having the problem.