I have a confession to make: I haven't been using my Nexus 7 that much over the past few weeks. Why? Because it has been suffering from horrible lag. Everything was peachy keen up until the Android 4.2.1 update, but that's a different story for a different day. For now, the lag is the important bit.
Then we stumbled across a new app called LagFix, which – get this – fixes lag issues on many devices, like the Galaxy Nexus, Nexus 7, Nexus 4, One X+, and more. Of course, the lag thing is a common issue, and is likely caused by a "well-known TRIM bug," which basically means that storage is "not properly TRIMmed when needed." So that's what this app does.