Finder "Open With" very slow I have the latest version of OS Yosemite (10.10.5) on a very powerful MBP (i7, 2.4, 16GB RAM).

When I right-click on a file in Finder and choose "Open with", "Other", the dialog window is very unresponsive:


it takes time (minutes) to populate the /Applications folder.
Scrolling the content of the /Applications folder is incredibly slow, the content takes seconds to move when I scroll the mouse wheel and I spend not less than a minute trying to reach the correct application I want to use.
When I finally reach the correct application and click on it, it takes 1-2 seconds to highlight the item I selected and another couple of seconds to enable the "OK" button.


This happens every time I select "Open with - Other" and not only the first time.

Is there anyone who can suggest a solution for this problem, it is incredibly annoying. I have never experienced such a weird behaviour on any OS X version.

Thanks.
Try rebuilding the Launch Services database, which populates the Open With menu. It can sometimes get corrupted, which can cause duplicate entries, slowdowns and other weirdness.

If you're comfortable with the Terminal, you can do this with a single command:

/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user


Otherwise, a free GUI tool like Onyx can do it at the push of a button.