I'm using PDFXchange Viewer to open PDF files, because it's much faster compared to Adobe Reader and I like the rendering better. I had to install Adobe Reader for testing purposes, and now Firefox opens every PDF document with the ultra-slow Adobe Reader. In the settings of Firefox, it still says that PDFXchange is used to open PDFs, but this is not the case.
How can I get rid of the Adobe Reader opening PDFs directly in Firefox without uninstalling something?