Your Mac slow? Disable Spotlight in Snow Leopard
27 Jun, 2011

For some time now I’ve experience my mac to be very slow. Opening Vim would take minutes. Creating a new Tab in iTerm would take more than 20 seconds. What the hell is going on - this is a brand new MacBook Pro! ~ After investigating, using Activity Monitor I discovered the following:

• CPU’s idling at 3-5% usage
• +500M free RAM
• +200G free disk space
• Negligible amount of network traffic
• Very high amount of disk I/O writes (> 450w/s)

What’s causing disk I/O?

So, something is using my disk. But what? The solution is to use the iotop utility:

sudo iotop -C 5 12

A common entry here is the mds procoess, which has an insane amount of BYTES. So, this mds process is causing a lot of I/O, causing things to get slow.

What’s the mds process do?

A quick Google search reveals that the mds process is actually the Spotlight indexer service.

Disable Spotlight

I don’t use Spotlight at all, so let’s disable it - preventing the disk I/O.

sudo mdutil -a -i off

That’s all. Spotlight indexing disabled. After a few seconds the disk I/O dropped from ± 450w/s to 0w/s. Vim starts ups again within a seconds. I’m happy.

Enabling Spotlight

If, for some obscure reason, you want to re-enable Spotlight, use the following command:

sudo mdutil -a -i on