Here's something that worked for me when ID was slow. I have always had success with exporting to IDML files, then opening these IDML exports. Something just seems to click and it works faster, my assumption would be that it doesn't like a font or something.
Also, have you tried deleting/rebuilding your preferences? Immediately after launch, hold down the Cmd/Ctrl + Opt/Alt + Shift keys. Click OK.
Hope this helps.
Are you exporting or distilling the PDF? What OS? Does this happen with a brand new file with only a single text frame?