I would recommend quarrying at least out of your personal loading distance of your base. That is at least 10 chunks away. The deal is that open quarry pits leave a lot of surfaces that needs to be rendered. So having loads of pits near your base would impact your fps. So yeah go far enough away to make sure you are out of distance of anywhere you plan to build.Im playing on my custom modpack and because i only have 1gb of ram i didn't add mystcraft, so! But would it help to make it far away?
I am guessing you don't have access to the Ender Quarry from Extra Utilities either? That would be preferable for quarrying in the overworld since it replaces all it mines with dirt and therefore don't leave open pits.