You could try ALT-TABing out and back into the game and the command "camera_kill". If all of this doesn't work, try talking to him from another direction. He gets stuck because you are in his way out of the warehouse...
How can i increase fps in vtmb?
Probably can't but don't see why you would need to, this is an offline Single Player game. Those places your having problems are either outside or where several AI are present. This is the earliest version of the Source engine and is not getting updates, just turn everything on max and have fun.
The most effective way to complete everything (doing this because I am testing and need to see amap) at the Giovanni mansion, is to take to her first follow her all the way down and stop just before zoning to the Embalming room. Then turn around and go back up do all the quests (I reactivated the Bruno quest) anyway you want, killing anyone who you want or not. Then just go down and zone, she technically zones ahead of you and has no idea you killed if you did.
Out of curiosity are you loading the map up to test or are you playing the level?
VRam:128Mb