Its not really going to get any faster than it is. Its a 2011 phone in 2013. It may or may not be running the latest version of the OS because Verizon cockblocks updates to it (and because of this they will likely never get another nexus device again).
Outside of making sure it had a decent amount of on board drive space left (supposedly this helps with the speed of the device) and uninstalling apps you dont need, nothing is going to make it blazing fast.
iPhone5 back to a old VZW GNexus is going to be a step back in speed and screen quality both, not to mention battery life. Its just.... an old and discontinued phone mate.
Fair enough. I guess I thought there were some roms out there that could make this sucker feel new.