Wading through treacle

To make progress very slowly and laboriously

e.g. I have been trying to organise my massive collection of books into some order. I tried by subject but too many couldn’t easily be defined or covered more than one. I tried by date of publication but I had lots of books that were originally published decades ago but I had a more recent copy. I tried by author but I have lots of technical reference books where that doesn’t work. I thought it would be a quick, easy task but it has been like wading through treacle!

- Wading is walking through shallow water.
- Treacle is a VERY thick, sticky syrupy liquid.