Note 2 stutter help

Okay so, first off, I'm not much of a noob in flashing ROMS and tools, I've had a bit of experience with a Samsung Infuse before, now I got this Note 2 and TouchWiz pissed me off, of course, now I need a lolipop ROM, I used ODIN to root and install TWRP recovery, also flashed a 5.1.1 "RESSURECTION" ROM, tried CM12 too, now the thing is, I'm getting a weird lag, this lag occurs randomly, lasts 2-3 seconds, followed up with a weird vibration, yes the vibrator vibrates the fone whenever this lag occurs... Now I tried a lot of stuff, except unlocking the bootloader because I'm not sure if it'll fix it or not, also after a while I noticed that it didn't detect my SIM card, could it be that my phone is refurbished? Everything else works ok but the lag makes it unusable.. The lag occurs on both CM12 and the other ROM so I don't think it's because of the ROM.. I'll revert to stock Kitkat using ODIN, but I really need to fix this. I tried Google for solutions but I can't seem to find anyone else having the same problem... So please help me out here mates