Edit4: as of the first of October 4pm of GMT time the game has received a patch on PS5 and my FPS problems are gone with the exclusion of autosave that still makes the game lag for few seconds, but otherwise it's a stable 60fps on performance mode which is absolutely amazing. The game looks and plays extremely well now, at least for me. Can't speak for other platforms of course!
Tried cutting the video shorter to just show the lag, but Reddit claims the video can't be used so fast forward first seven seconds. The graphics are magnificent, but the performance issues are constant when playing on performance mode. I also switched the camera mode to classic as the modern FOV is extremely cramped, but that muffled audio regardless of voice volume being 100/100 in settings. I'll be updating issues in here as they come across
Edit: restarting the game resets all the settings to default and now it looks like my FPS is stuck to below 30 on performance mod, except cut scenes which look crispy and smooth the way 60fps should
Edit2: lot of people here scream "can't criticise it's free", but did you ever stop thinking that although this is free for me there are thousands upon thousands who bought this from sale just to experience the game for the first time? Also the purpose of this post is to inform other users about the problems so if anyone is about to buy the game, they have more knowledge regarding the current state.
Edit3: turning off graphic settings like vignette seems to reduce the stuttering, but whenever the game autosaves it lags like hell and the autosave does happen in combat as well. Restarting the game causes all of the settings to reset and it also logs you out and requires you to log back in, if you want to connect your CDPR account for extra goodies