I'm not sure if this is normal or not, but Activity Monitor is not showing Lightroom as a 64-bit process. If you are running Lightroom, could you check if this holds true for your system as well? The first screenshot is Activity Monitor when booted normally. Lightroom is about 1/3 of the way down the list. The second screenshot is booted into the 64-bit kernel. Lightroom works fine, but still doesn't show as 64-bit. What gives?