Some advice for Galaxy Nexus and Nexus 7 owners
Right after I updated to 4.2 from 4.1.2 on my Galaxy Nexus I was quite shocked. The OS as a whole became pretty unstable, with launcher crashes multiple times a day and everything started seeming a lot laggy as compared to plain old 4.1.2. Which was especially surprising as I had flashed a stock image straight from Google itself and I had performed a complete wipe. I kept using it for 3 weeks, cursing myself for ever upgrading and today I came across plenty of forum posts by people facing similar problems on their Galaxy Nexuses and Nexus 7s and came across a post suggesting that I should wipe my cache partition. So I went into CWM recovery and wiped my cache partition and ever since then, my phone has become buttery smooth.
In fact, before the cache wipe, even opening the Chrome browser resulted in a launcher crash, where pressing the home button would yield a completely empty homescreen and it took a while for widgets to load. After the wipe, I tried stress testing it, with 10 Chrome tabs, 3 stock browser tabs and then playing a round of Subway Surfers and going back to Chrome from within the game, yet my phone remained buttery smooth.
So just remember to wipe your cache partition if you are experiencing any problems on the Nexus 7 or Galaxy Nexus after the 4.2 update!