I sometime sdo a recompile all equations because I make a change to the preamble I want reflected in all the equations in my document. That is slow, no it's slooooooow and it's painful at present. The up side is, it works, and that is awesome. But I would like to sugges some useability improvements:
1) It seems that if I interact with LibreOffice in any way, I get compiled equations popping up in odd places. This even spance Writer windows. So I am reocmpiling in one window, and move to work in another document and the recompile process starts dropping images into my new document. Basically it seems to be working with the UI rather heavily which, if it must do, it should perhaps firmly lock all UI interactions while it's running to stop these odd image drop offs. The up side it seems is that they still appear where they should have (though not sure if I see the prior or posterior image there ..., at least the original doc is not corrupted).
2) Given how long this takes, it is worth considering a slicker approach. Alas I'm not savvy on LibreOffice coding enough to make speicifc suggestions. A generic idea might be, to spin the image generation off into a background process and have it generate all the images one by one in temp files somewhere perhaps, then as a last pass go and walk the document in the UI inserting them. Of cours eit may not be so easy or possible and perhaps you are doing it the only possible way the LibreOffice API makes possible.