I have tried slimkat, aokp, cm11 and they all seem to be getting slower everytime i flash a new rom
I think this started to happen when i first attempted to do a full backup, the phone froze during the process because it was running out of memory. It was a pain to get it working again because it was sooooooooooooooo slowwwwwwwww.
Then i just booted to cwm did a full system, data, cache wipe and installed a new ROM, during the initial steps phone starts stutering, no matter what rom it is.
My guess is that there are still some files somewhere causing the problem.