I can’t find one person who has been using the Nexus 7 for an extended period of time, and hasn’t seen a massive downgrade in performance. Just what kind of downgrade are we talking here? I cannot pick up my Nexus 7 without experiencing problems like a lag of ten seconds, or more, just to rotate the display; touches refusing to acknowledged; stuttering notification panel actions; and unresponsive apps.
I tried the basics at first, like a factory reset. I then moved onto drastic measures, like rooting and installing CyanogenMod 10.1 (which I thought would surely fix everything, since I’ve used faster devices with lesser hardware, and performance problems were merely a lack of software optimization). And nothing seems to work. Using CyanogenMod worked at first, but things have slowed down dramatically again. I’ve tried uninstalling most of my apps. Using replacement launchers. No widgets. Nothing works. And even if any of those things did work, it would still be terrible looking for Google... More at Android and Me.
That's a worry, but it does seemed to be backed up by many users on Twitter as well. There is also a theory that cheap memory is causing the problem-
One problem at the core of the issue seems to be related to early failure of SSD memory. Unlike the conventional mechanical hard drives, which typically either fail immediately or last for several years before nearing the end of their useful life span, solid state memory progressively wears out as it's being used.
High quality flash memory can provide a significantly longer lifespan than cheaper versions, but it also costs more. All SSDs requires intelligent, low level software to identify blocks that are no longer working and work around them.
SSD also requires routines for handling cleanup of erased data, as solid state memory must be erased to zero before being rewritten to, a step that isn't necessary for conventional magnetic hard drives. If these "garbage collection" tasks aren't performed properly, performance degrades over time. More at Apple Insider.