A shot in the dark
I remember seeing such slow opening of document a while ago, and spent some time trying to determine the reason. It turned out to be a challenge posed to the pagination process, as @EarnestAl also suggests: Nearly all paragraphs were set to “keep with next”.
The keep-with-next setting made Writer work hard to try to keep everything (100s of pages worth of text) within one page.
This can happen when converting documents from one file type to another. More likely is that the paragraph style was set to e.g. Heading 1, and then the content was manually formatted to appear as text body.
Suggestion
Which procedure is the best way to solve this kind of issue depends on how the formatting was applied in the first place. With a document of the magnitude as indicated, major repagination takes time and may look messy while the process is working. You should leave initial diagnostic measures and testing to experienced users, not attempt to patch up your document in one go.
At best, make a copy of your document where you keep only a few pages, and attach that file to your question here.
An actual odt file is required. A screenshot or pasted text from your document is of no use.
An attached file sample allows us to determine whether this is the cause (and also search for other possible causes), how it may have happened (settings may be applied on several “structural levels”) and consequently, which way it is best to proceed.
“Save as” from Writer will work, but it is easy to make a mistake. In my experience, the safest is to first make a copy within your file manager app.:
- Right-click your document file
- Select Copy
- Right click within folder.
- Select Paste
(The file manager should then suggest an alternate name which indicates that this is a copy.)
Then edit the copy, removing most of the content so the file size is reduced, permitting upload here. 5-10 pages should suffice.
Remember that this is a public place, so take care not to upload confidential/sensitive matter.
Keep-with-next is a useful setting for headings and other captioning. In some cases you will want it for list elements, and it also happens to be useful for other content occasionally, but in most cases you don’t need it for text body content.
