If you are one of the thousands of users who, seemingly out of nowhere, experienced performance issues with your original Nexus 7 tablet, an update to Android 4.3 could substantially improve matters.
The choice of low-quality eMMC and a poorly-performing memory controller in the Asus-built Nexus 7, combined with a lack of garbage collection in filled-but-unused sectors of the memory, contributed to slowdown over time. Wiping the device clean temporarily fixed the problem, but once the blocks were filled again with apps, music and other files, the tablet quickly began to bog.
Android 4.3 introduces TRIM support to the operating system, including the Nexus 7, which is a standardized cleanup procedure for compatible file systems that detects unused memory blocks and, when the device is plugged in and not in use, wipes them clean.
According to Anandtech’s Brian Klug, “TRIM (and its equivalents) establishes that communication between file system and eMMC/NAND controller. When unused blocks are TRIMed at the OS level, a signal is sent to the eMMC controller telling it that it no longer has to track that data. A good controller will then schedule those NAND pages/blocks for garbage collection/recycling, thus improving performance.”
While this will most prominently affect the Nexus 7, which is badly in need of such performance improvements, TRIM has been found to run on all Nexus devices running Android 4.3, and should be up to the OEM to implement when specific carrier models are updated in due time.