Writer hangs intermittently while typing / inserting text beyond the visible area

[Christian Pernegger]

This is a relatively fresh install of 22.04, fresh LO profile.

My toddlers like to "type big letters", read: I open a new Writer document and crank the font size up to the max, they peck at the keyboard, or mash it, or simply hold a key down to watch the letters flow down the page. So there tend to be long lines of letters and punctuation, largely unbroken by spaces.
This wasn't a problem in 18.04 But 22.04's Writer can't keep up. At all.

Whenever the text reaches the bottom of the visible area, which, given the font size, happens pretty quickly, instead of simply scrolling down Writer will just hang for 5+ seconds. It'll snap out of it eventually, but ... This is 100 % reproducible.

What's more, deleting such a "work" (ctrl-a, del) can on occasion take 10 seconds, during which Writer, again, hangs. We're talking 1 page, 2 tops. That one is not fully reproducible, sometimes it is instantaneous.

I use Writer a lot, or used to, the 18.04 version, I mean, and these hangs feel familiar—from documents tens of pages long, with multiple images, tables, and other elements that complicate the layout; the kind that happens when writer "can't decide" whether an element should go on the next page or not. But not from short documents that have nothing but text.

You don't need to be a toddler, either. Just copying a decent-sized passage of plain(!) text and inserting it into a new Writer document (ctrl-v) repeatedly will do. As long as it fits in the visible area / on the page, it's inserted instantly, otherwise it'll hang for a couple of seconds. Again, 100 % reproducible.

This box is four years old, but a 12-core with 32 GB RAM should be enough for smooth word processing, no?

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: libreoffice-writer 1:7.3.7-0ubuntu0.22.04.3
ProcVersionSignature: Ubuntu 6.2.0-1009.9~22.04.1-lowlatency 6.2.13
Uname: Linux 6.2.0-1009-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Thu Aug 10 18:28:01 2023
InstallationDate: Installed on 2023-08-02 (8 days ago)
InstallationMedia: Ubuntu 22.04.2 LTS "Jammy Jellyfish" - Release amd64 (20230223)
SourcePackage: libreoffice
UpgradeStatus: No upgrade log present (probably fresh install)

[Christian Pernegger (fallenguru)]

Found the culprit. I thought I hadn't changed any remotely relevant settings yet, but either way Options → LO Writer → View → Smooth scroll was checked. I went back and forth a few times, no doubt about it. One-click method to turn Writer into a laggy mess.