Can someone who has Thunar and tumbler installed, please download the pdf file discussed in Why do large PDFs take so long to load in Linux PDF viewers... ?
Once the file is downloaded, use Thunar to open the folder containing the downloaded file. Do you see high and prolonged increased CPU usage attributed to tumblerd?
I've been using Thunar for quite a while and didn't have any such problem before. I'm wondering if the downloaded pdf file is to "blame". Could it be because it's mainly a scalable graphic image? I doubt it's just the size of the file. I have quite a few much larger Full Circle pdf files as well. Tumbler didn't have problems with those or with the images in them.
I'll be looking at this a bit later, but for now, I ran sudo apt-get purge tumbler.