I just update my Ubuntu 12.04 to the last version Ubuntu 12.10, i hope an nautilus improvement on speed, but not today.
Of course, I decide change it!

sudo add-apt-repository ppa:marlin-devs/marlin-daily
sudo apt-get update
sudo apt-get install marlin

"Marlin" its a minimal reduction of Nautilus and really offer the promise.

Homemade Benchmark

• Nautilus: 7" until files show
• Marlin: 2" until files show

For now, i choice Marlin. And you?

EDIT!

Marlin on my machine crash sometimes... later i try PCManFM and...

• PCManFM: 1" until files show

Awesome