There are all kinds of reasons for a phone to lag.
1. too many active widgets
2. too many installations and on installations of software that left junk behind
3. antivirus software that isn't keeping you informed of when it's scanning in the background
4. frequent checking of mail or weather updates
5. low disk space
6. and more.
Solutions, root and ROM, or factory data reset. However, nothing here will help an old phone. It's the same thing that's going to happen at some point with an old computer. Eventually you'll need to replace it.
I have none of those listed, furthermore, why root my phone? Thought the whole purpose of Android over iOS was the fact you could do more. Apparently, they are slowly but surely taking that freedom away.
I remember playing with Android 1.6! You could do ANYTHING on that, then I remember 2.2, very very customization friendly. Even 2.3.
NOW, it seems they have tied up a lot more features, hence all of this rooting, which is equivalent to the iOS "Jailbreak". The annoying part is I went with this Droid thinking 4.0 and 4.1 would be similar to older versions, but they are not. Hell, FLASH isnt even natively supported anymore ?????????????????????
I dunno, loved the phone at first, but slowly but surely missing my "dumb phone", and before anyone asks, why did I get this phone, was I waaaay due for an upgrade, and wanted something "smarter" like the GPS and Google Now, etc... but weighing out the $30 extra a month and below par phone thats easily breakable vs. a phone that just was for calls and txting and didnt care if it broke... the dumb phone slightly comes out on top.
I'll see how much I can get for it online, maybe just switch back to old Env Touch.