Lightroom: Slow as Molasse on a Cold Day

A friend/customer of mine, Rich, was having problems with his Lightroom 3.3 (current). It was as fast as molasses on a cold day.

I tried to help him over the phone, no luck. Time for TeamViewer. It's some software so I can log onto his computer without having me to drive there.

Yes, it's slow, very slow. A quick looking around, nothing too obvious. Switching to the Grid View is extremely slow. I start the task manager to see what's happening and I see a very high IO, it's the one in red. IO is Input/Output. It's usually related to disk IO, but it could be USB IO…

The question is what's causing the heavy disk IO? I asked Rich if he knew. Nothing changed, no new install. It's be getting slow for the “last while” with no idea for how long is the last while. I start looking around, checking the Lightroom catalog… No, it's working fine…

I keep on looking, then suddenly the “stroke of genius”. The problem is the antivirus. The antivirus has real-time protection. Meaning that the antivirus checks for every disk write and Lightroom does a lot of disk reads and writes. Every time Lightroom builds a preview, it saves it to the preview directory. Every time you switch to the Develop module, the 1:1 preview is built (if it doesn't exist yet), saved and displayed.

Rich uses the Microsoft Security Essentials, but it's the same for all the other antiviruses.

Settings:

• Excluded files and location: I excluded the directories of the Camera Raw Cache settings (from the preferences|file handling) and of the catalog (from the catalog settings|location) .

And we were almost zooming again. I got him to run the Windows Disk Defrag 4 times to reorganize the disk.