If you have a Nexus 7 (2012) that you are frustrated with because it has become impossibly slow, I suggest you flash back to a previous Android release. For the uninitiated, here are the steps:

Your bootloader is still unlocked, so sometime soon (you don’t have to do it immediately) you reboot into fastboot mode and run fastboot oem lock to re-secure your device. This prevents a hacker from bypassing the password or pattern login by unlocking and then rebooting your device into a mode where they can read its contents.

Restore your backup by copying files using MTP or by using adb push.

I hope this helps! There are other, more complicated things you can do (like flashing custom “ROMS”) but I prefer to stick with the vanilla Nexus images.

Good luck!