As far as I know, there is no way to turn off popup messages presently.
I don't know about anything new in regards to the weird tome, but there have been some developments in regards to the scroll of omnipotence apparently as a post gate closing quest/thing to do which requires you to get a new guaranteed artifact in the final level of the Minotaur maze beforehand. (The wiki's not finished yet and I don't ever do the Minotaur maze, so I haven't checked for myself yet.)
Cant help with the ascii problem as It doesn't scale right on my computer so I don't use that mode anymore, but If I had to guess what was causing the lag I would imagine it has to do with the health bars now over the monsters heads. (I don't think you can remove that either.)
Major new danger - Vile spirit's - basically a shadow version of a previous character that died (or a friends character if your steam friends also play adom) they have the stat drains of shadows and all the equipment of the dead character and can appear wherever that character died which can potentially make a very dangerous monster for a character that comes after a trap door death in VD1(had that happen, fought and died to the character I had just lost on VD 1 to a trap.) fortunately these can be turned off by editing the config file. (I think they made it where you can disable them in the in-game settings also.)
Boss monsters will occasionally spawn now - usually not too dangerous, but also usually a lot harder than their normal counterparts. (I.E. boss goblin much stronger than regular goblin.)
"you are the only cactus in the garden of my life" Gomez - Adams Family