Workaround for the Slow Open / Save Dialog Box Problem in OS X Mavericks
A fair amount of Mac users running OS X Mavericks have discovered a peculiar slow speed issue when attempting to use various actions found in the File menu, including the Open, Save, and Export dialog boxes. The problem manifests as an intensely slow lag when trying to use the Open or Save dialog windows, where the spinning beachball shows up, spins aimlessly for 3-15 seconds, followed by a lengthy slow delay before any files or folders populate the file action windows and allow a user to proceed.
This behavior is almost certainly a bug and not all users of OS X Mavericks encounter the problem, thus if you have not experienced this issue there is no reason to make any changes. That said, plenty of commenters in our Mavericks Finder speed fix article also have the slow dialog box problem, and thankfully a workaround solution has been found on Apple Support Forums (thanks Droo!) that may work for some other users encountering the issue.
Note this solution is a workaround, not a proper fix. The slow Open/Save issue seems to pertain to accessing network drives, and this workaround prevents network shares from automatically mounting. Accordingly, this will not be a valid option for users who map network drives for auto mounting, or for users who rely on automating network shares in any way. You must edit a system file using the command line, if you are not comfortable with Terminal then waiting for an official bug fix is probably a better idea.
Launch Terminal and enter the following command:
sudo nano /etc/auto_master
Enter an admin password when requested, then find the line that says “/net -hosts ….” looking something like this:
/net -hosts -nobrowse,hidefromfinder,nosuid
Use the arrow keys to navigate to the front of that string, and then place a # (pound sign) in front of the / to signify that it has been commented out, it should now look something like this:
#/net -hosts -nobrowse,hidefromfinder,nosuid
The modified /etc/auto_master file should now look like this, the #/net has been highlighted:
Now hit Control+O followed by return to save the file, then Control+X to exit out of the nano text editor and return back to the command line.
Now you must flush the automount cache, so type the following command string:
sudo automount -vc
Now you should be good to go, so exit out of Terminal and try to access any Open, Save, or Export dialog box window again. The slowness should be gone completely, and you’ll be back to speedy file interactions through the dialog windows as expected.
This bug has been encountered and reported enough that we can assume a solution from Apple is likely to be due in a future OS X Mavericks update, be it 10.9.1 or otherwise. If you do use this automount workaround, remember to remove the # from the /net entry in auto_mount if and when an official bug fix arrives from Apple.