[artful123]

This worked instantly for me. No more lagginess! Seems to have helped many others as well (scroll down to see comments).

[xQuencher]

I unrooted the device, relocked the bootloader and flashed the stock ROM for 4.1.1 and updated it. Performance greatly increased.

[Small_law]

There is mention on reddit and elsewhere that making sure Google Currents is not syncing (uncheck the boxes in the settings menu in the Google Currents app and reboot) does the trick.

Thought it was BS. It is not. Give it a try yourself. My N7 is back to its old self.

[B. Diddy]

I've always been a little leery of Google Currents. It looks nice, but I remember comparing it with Pulse on my Razr Maxx and Acer tablets, and found that Currents took up a huge amount of space compared to Pulse. I can't remember if it slowed things down on those devices, though.

As a general rule, I usually turn background sync off for any app. It's easy enough to tap the refresh button myself.

[Small_law]

Um, yes. My N7 is much faster and more stable now. Again, this coming from a somewhat uneven source, I thought it wouldn't work. But it does seem Google Currents could be to blame.

To be clear, open the Google Currents app, go to settings, uncheck all the syncing boxes, exit the app, reboot your N7. Does this help? I don't remember if I had any of this enabled originally or if the 4.2 update did it. I am seeing a marked improvement.