Saving calc file really slow

I have a spreadsheet file that suddenly started taking a long time to save, 35sec. It’s only 286kbytes.

libreoffce 4.2.8.2
xubuntu 14.04

Maybe you have something lost in the file, first test with the navigator, second clean the format for the cells beyond the used area or with lost unused data. [Ctrl+End] helps to find the bottom-right cell of the range with data…