Rob Photosby wrote:
The lightroom folders have two files.   The smaller file is the database of commands that tell lightroom how to process each image.  The far larger file is the collection of previews for each photo in the database. 

If you are jammed for space, you can tell lightroom to discard previews after 30 days.  In the extreme, you can discard the whole preview file, but be careful not to relocate the original photo files because it can be tricky to rematch the data files with the photos.

On the other hand, relocating the folder, as you have done, is the best solution.

Yeah, that.

Adobe creates gigantic cache files and stores them forever, for some reason.  You can clean them out perfectly safely, but if you're looking through lots and lots of folders of images to decide which ones to process, all those previews are stored for quick retrieval, even though you'll likely never need them.  It's done to save you time so they only have to render once.  But it's absolutely ridiculous how much space it eats up.

You can move your cache locations to a larger, slower drive (which you've done) or regularly clear those cache folders do deal with the situations.