Galaxy Note II Unresponsive for minutes at a time

Question

I'm on my 3rd galaxy note 2.  My first one had an overheating problem that caused the battery to last for 2 hours even though it was idle.  They ended up replacing it for me.  My 2nd one was actually perfect.  I had zero problems with it for nearly a year until the day after the 4.3 update, the screen went off and never came back on.  I just got my replacement about a week ago and I'm having an issue with the screen becoming unresponsive for minutes at a time.
I factory reset the phone yesterday thinking that maybe I had a rogue app installed but it seems that any time I try to launch a game or if I try to browse the internet while an app is updating, the phone is unusable for a few minutes.  It's like it can't multitask. Eventually it'll come back with the phone at my home screen with my background image gone, but eventually it comes back too. It's similar to when windows explorer crashes and it reloads. I'll go through the same process for 2 or 3 more times before the game finally launches or the internet browser is finally usable.
Before I call this phone defective, I was wondering if it's a problem related to 4.3 that I should be aware of?  I installed a monitor and it looks like with no apps open, from a fresh reboot my ram is 50-80% used which doesn't leave much room for opening apps or playing games.  I even installed a virus protection and scanned for a virus (i know viruses on smartphones is a stretch) and it returned no issues.
Any ideas?  I could factory reset it again, but I just did that last night and it didn't help still having the same problem with very minimal apps reinstalled.  One note, I factory reset it with the restore from backup functionality turned off, so the apps I did install were from scratch, not my google account.

Answer 1

I decided to call in.  I tell the rep my problems and he tells me to launch the phone in safe mode. Done. I could reproduce the issue. It then says wifi unstable.  The phone freezes with wifi on. Tells me to turn the wifi off. No more freezing while in safe mode, I guess wifi is the problem didn't think that was an issue before. He tells me that wifi issues have been reported but none of those issues cause the phone to freeze, he said that samsung told them to tell customers to turn that feature (ie: wifi) off until the next software update. He said samsung is working on a fix for the wifi issues but said there's no eta. I asked him for his gut feel and he said phones that are newer than 18 months normally get priority, given that the note 2 was release in november of 2012 and we're in 2014, that he estimated 3-4 months for the next update. I know I can't hold him to that but even if he's right, I have to leave wifi off for 3-4 months?...Now to the best part, "Since there is no freezing with wifi off in safe mode, and in safe mode the phone behaves in the state samsung designed it to be in, I've determined that it's not a hardware or operating system issue, so there's nothing I can do for you. I'm sorry I couldn't send you a new phone or resolve this problem for you, I hope you find a solution for the software issue you're having, good night."
Rather than get mad I realized I wouldn't get anywhere with him so I didn't try to push the issue. I know I have unlimited data so it's not that big of deal, but wouldn't you consider the phone not working regularly with wifi turned on a hardware or os system problem?  It's not like I can uninstall and reinstall wifi.  The drivers are embedded in the system and since it's a refurb phone, who's to say that the parts that were refurbed are really factory oem?
Now I'm stuck with a phone that is unusable randomly for 3-5 minutes using the phone normally with the mobile network/wifi because the agent didn't consider the problem to be hardware or os related and the only way to keep it from having issues is to not turn on wifi and keep the phone in factory default settings.
I'm not going to threaten to leave or go somewhere else because it would serve no purpose, maybe that's why there was no attempt made to help me other than saying no from the beginning of the conversation, but in my 15 years of being a loyal customer, you would think "i hope you find a solution on your own" would be after sending me a new device if the problem persisted.