Issues with Writer on Linux and larg(er) pictures

I’ve been using LibreOffice for a very long time and I’ve never ran into an issue I could not solve with a bit of googling.
Now however I moved from Windows to Linux (Ubuntu) and face an issue I cannot get behind.

It’s partially the same as Image won’t paste if too large, but it goes beyond that.

I use a lot of images in a specific document type, largely as markers for sections, jump points and the like.
On Windows I would simply copy&paste them as Fletcher Moore described, which on Windows worked without any issues, but on Linux requires me to first reduce the size of the image to <500X300 pixels.
Otherwise I experience the same freeze and nothing happens as described in Image won’t paste if too large.
Maybe noteworthy: I am still on the same hardware where it worked on Windows.

Apart from the extra effort, for some use cases that is too small. So I would import the images, which works.
However I noticed that once I have large images in the document, even if there’s almost nothing else in there, Writer slows down to a degree where I can sit there and watch what I typed being slowly written seconds later and (worse) it’s mostly gibberish as some letter will show up in later words and things like that.

The problem goes away if I reduce the size of the images again, but now they look bad on the projector.

LibreOffice Version information

Build ID: 1:5.4.5-0ubuntu0.17.10.5
CPU threads: 4; OS: Linux 4.13; UI render: default; VCL: gtk3;
Locale: en-US (en_US.UTF-8); Calc: group

I’ve tried to increase memory cache RAM (My machine has 8 GB of RAM) as I did on Windows to solve performance issues (with a lot of images, not just one or two), but it had no effect.

So something seems to be very different in how the Writer handles Images on Linux.
Is there something I’ve missed, some setting I could try?
So far the only workaround I’ve found is to finish the document with low-res images and do the image import as the last step (so I won’t have to write afterwards).
Any help would be much appreciated.