LibreOffice Impress very slow

So I started LibreOffice Impress to make a presentation for school, but it ran extremely slow on even the most basic tasks (IE typing, formatting text)

The CPU usage seemed to constantly cap out at 25%.

CPU: x4 1.5GHz ARM Cortex-a72 – overclocked to 2.147 GHz
Storage device: 32GB microSD card C10 U1
GPU: VideoCore 6
(Raspberry Pi 4)

Who’s distro are you using? you may want to look here,
The maintainer of this distro uses pi’s extensively and has been making optimizations where he can. He might be better to ask about this.

CPU usage of 25 % in a quad core setup usually means, that one of the four cores is totally busy. Since Impress is not parallelizing (running on more than one CPU core) I think there’s nothing you can do except running it on better hardware ;-).
Other suggestions would be to decrease CPU load of Impress somehow. Is it really Impress that’s blocking the CPU (have a look in top for example)? Which distribution are you using? Is Impress maybe rendering in software and not on the GPU? Is it helpful to decrease the screen resolution (that would point into the software rendering assumption)?

With the CPU thing, that’s what I thought was happening. It is in fact ‘soffice’ taking the CPU. I am using Raspbian; I don’t know how I’m rendering, but I can try the resolution thing later.

LibreOffice 7 still has the massive issues with hanging and endless inactivity and extremely slow operation. It’s not a question of CPU or memory or so. Sometimes LO is very fast so it is not a question of hardware. How fast LibreOffice can be is shown if you start it in “safe-mode” (just with the option: libreoffice7.0 --safe-mode). Then some incomprehensible and weird options are shown (that do never really help). And it’s runnging fast like a rocket.
Did not help: Change or disable Java version. Start or stop anti-aliasing. Did not help: Delete .cache-folder to force new ini-files.
Helped a little: Eliminate invalid path to templates.
One thing that helped a lot (for a short while): I switched the document type for standard format to “Globaldokument”. Suddenly everything was fast as expected.
Apparmor is not the reason, I disabled it for a while. And the logs do not show severe “denied” issues.
However, this frequent hanging of start or stop or documents is really cumbersome.
Two acquaintances have exactly the same problems, we see it on many different machines. The bull**** never stops …