"Fetching..." Behavior in Finder "Open With" Menu in Yosemite
I had a similar issue and the 'Fetching...' was taking many seconds. I just reset Launch Services with the following command:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -seed -r -f -v -domain local -domain user -domain system