Slow sorting

[petermross]

I work with some reasonably large spreadsheets, typically around 2000 rows by 27 columns, around 250kb in XLSX format. There is a title roiw and each column has a filter. Some cells have associated comments (small red triangle in upper right corner), and those comments are typically each one of about eight variants, each about 375 characters long.

Sorting performance varies enormously depending on how many cells have comments: if about 100 cells contain comments, sorting the entire block below the title row is virtually immediate. If about 1000 cells contains comments, sorting that block takes almost five minutes! I am sorting on a single column that contains only people's names, and there are no comments in that column. Is this behaviour to be expected or is there some issue with sorting that sort of data?

Background information: I am running Arch Linux, kernel 6.11.6, on a Ryzen 7 desktop with 16Gb of memory and an nVidia RTX 4070 graphics card.
I am using Planmakernx S1218.0824. I am not running any other significant program at the time, load average is just over 1 while the sorting is happening. ps reports that planmakernx is running normally, multithreaded in the foreground process queue while the sort is happening.

Apologies, I cannot immediately supply a test file, the data I am working with is confidential.