If I try to pick up the drawing of all weapon, the game start lagging and run about 5 FPS
Mentioned that it Duplicates.
The game doesn't really lag, I don't believe, though.
You just assume it does because the /drawing/ lags.... Though. I could be wrong. Your computer is not my computer, and for you, it could seriously be lagging.
take them to the incinerate every time you reload the game to prevent them from piling up.
Rotate them a few times to get them unsyncronized from each other - They're identically stuck together, and forcing each other to move in sync with one another when you grab one of them, so it may take a few turns to get half of them to a different angle
Once they're unsynced with each other, it'll get a lot easier and the game will render/process the pile slightly better, and every time you free one, too.
And the incinerate can delete them from existence all at the same time if you can't separate them, just be patient while dragging them to the window by workbench, and then go through or around the window (you can crouch jump through the windows) and take it through and around to the incinerator.
Its possible though that if you start and stop playing a lot, they may multiply without your action, and may cause the game undue strain - 3-10 of them might lag themselves, but 40 of them might cause the game to take an hour to load into, and 20 more might crash the game on load
Ot
100 of them might still only lag themselves. - who really knows, honestly, I find it just best to keep them in check after learning they duplicate. "better safe, than sorry"