LibreOffice Impress vs. NFS Network Shares vs. Caching

Whenever I put together a presentation, LibreOffice Impress gradually grinds to a halt with images in the slide thumbnails repeatedly updating and never stabilizing; eventually, LO crashes and sends a crash report to whoever’s watching. This may be due to my enthusiastic use of images to get my point(s) across, although I’m just not gonna back down from that position:

That’s a screenshot of a small thumbnail, enlarged for visibility, so it doesn’t look that crappy in real life.

Perhaps the problem arises because I insert the images as links, rather than embedding them to create a monolithic presentation file roughly the size of all outdoors?

Searching with the obvious keywords produces tantalizing hints concerning LO’s file locks clashing with NFS network share locking, which seems appropriate for my situation with all the files living on the grandiosely named file server (a headless Optiplex) in the basement.

The suggestions include making sure the NFS locking daemon is active, but I have NFC about how that might work in practice. The lockd daemon is running, for whatever that’s worth.

Seeing as how I’m the only one editing my LO presentations, disabling LO’s locks has little downside and requires tweaking one character in one line inside /usr/bin/libreoffice:

# file locking now enabled by default
SAL_ENABLE_FILE_LOCKING=0
export SAL_ENABLE_FILE_LOCKING
<<< blank line to show off underscores above >>>

After a brief bout of good behavior, Impress resumed thrashing and stalling.

Copying the entire presentation + images to the SSD inside my desktop PC didn’t improve the situation.

More searches on less obvious keywords suggested disabling the Impress “background cache”, whatever that might be:

Tools → Options → Impress → General → Settings

Then un-check the ☐ Use background cache item, which may be the last vestige of the now-vanished memory usage and graphics cache size settings from previous versions.

In any event, disabling the cache had no effect, so it’s likely a problem deep inside LibreOffice where I cannot venture.

It autosaves every ten minutes and I must restart it maybe once an hour: survivable, but suboptimal.

There seems to be an improvement from Version 6.0.7 (Ubuntu 18.04 LTS) to Version 6.2.8 (Manjaro rolling release), although it’s too soon to tell whether it’s a fix or just different symptoms.