Bug 138295

Description:
Every time I select a whole column, Calc gets busy while "load document". This makes it almost unusable at times.

This happens when I start LO from terminal (Linux) with the following command:
SAL_USE_VCLPLUGIN=gen libreoffice

I got to that point because my calc is very very slow even with empty files and I was trying to diagnose the problem. After reading some post in the web I tried that way of starting LO (SAL_USE_VCLPLUGIN=gen libreoffice) and I see that when I select a whole column Calc shows "loading document" in the status bar, most of the times TWICE (for each time I select the whole column). And the document loading is quite slow, so this makes using calc very very slow.

Libreoffice starts very fast, that is not the problem. The slowness starts when using Calc (and at some extent, Writer, but I don't really use the other components of LO so as to say if they're affected as well).

All other (non-LO) applications work very well in my PC. I am using a light-weight GU/Linux distribution (Lubuntu 20.04) running on a SSD drive and 8BG of RAM, and it works quite fast in general.

If I start LO Calc in the "normal" way, I experience the slowness in responsiveness but I do not see the "loading document" in the status bar. When I start LO Calc from terminal using the above command, I experience exactly the same waiting times but I do see the "loading document" in the status bar.

What is this "loading document"?
Why does it happen two consecutive times most of the time?
Why does it happen when I select a whole column and not for other events?
Would it be possible that it is slowing down my calc installation?
Would it be possible to disable it? It seems that if I avoid that "loading document" the operation would be much faster.

Steps to Reproduce:
Linux
1. open console (aka "terminal")
2. type SAL_USE_VCLPLUGIN=gen libreoffice
3. On the menu in the left, select "Create"... a new Calc spreadsheet.
4. Now you have an empty, new Calc file. 
5. Select any column (whole column, this is click on the letter to select the whole column and not a particular range of it)

Actual Results:
a- On the bottom left part of the Calc screen, I see "Document loading" for a bit (with a progress bar growing to the right). 
b- Then it ends, and automatically starts again.
c- Then it ends and you can continue working. 

Most of the times the sequence is like that above. But some times it just shows "document loading" once.

Expected Results:
Since I have no idea what is "loading document" and I don't really know what to expect from starting LO with that command, I can't say what is the expected result. 
But of course one would expect that this behavior is a bit awkward at least.

In previous version (maybe before 7.X?) I never had any trouble. Whole-column selection was as fast as any other command and even with large files (eg 4000 rows) I had only slight lag response. 


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 7.0.3.1
Build ID: 00(Build:1)
CPU threads: 4; OS: Linux 5.4; UI render: default; VCL: x11
Locale: en-US (en_US.UTF-8); UI: en-US
Ubuntu package version: 1:7.0.3-0ubuntu0.20.04.1
Calc: threaded

Additional information: this is not the default installation which comes with Lubuntu. I had to change it because it has a bug or something that produces empty PDFs. So I uninstalled it and reinstalled from LO PPA. Also I tried installing using SNAP and appimage and the problem persists.