Android - Why does my Android device slow down after successive ROM updates without wiping?

I've come up with one potential answer myself: TRIM

Solid state disks (SSDs) and some flash memory require the operating system to perform a kind of housekeeping task to maintain the efficiency of the device.

The operating system command TRIM is explained in this AnandTech article:

• http://www.anandtech.com/show/2738/10

Its applicability to certain Android devices, including my Samsung Galaxy Nexus and ASUS Nexus 7 is explained in these XDA Developers threads:

• http://forum.xda-developers.com/showthread.php?t=2104326
• http://forum.xda-developers.com/showthread.php?t=1971852

An XDA member wrote an app called LagFix which purports to exercise the TRIM maintenance function, thus restoring write performance for the device.

Since I recently performed a complete factory reset, I'm no longer having performance problems and thus I can't directly corroborate the purported benefits of LagFix. If I'm in a position where performance is suffering, I may do some benchmarking and see if LagFix improves the situation.

Please be aware if you plan to try LagFix that there are some devices that have chips that do NOT play nice with this utility. These chips have what's come to be called a BrickBug, and if you run LagFix on one of these devices, you will irrevocably brick your device.

I highly recommend you follow the advice and read the LagFix FAQ. It points to a utility which can tell you if your device contains a chip that may suffer from the BrickBug.

• http://forum.xda-developers.com/showpost.php?p=37029420&postcount=122