alright so i am one of the poor fellas who at some point in the game experienced constant crashes when coming close to the main building at Camp McCarran.
being in the habit of constant paranoia-saving i was able to back-track at which point McCarran becomes CDT ridden and therefore inaccessible (except of the console.

the exact point (in my case) is when i'm on the Oh My Papa quest of the Great Khans. Before i hand the slave ledger obtained from the Fort to Regis it works fine (even after various fast travels to McCarran). However, as soon as i hand the ledger to Regis and travel back to McCarran i get the crash when trying to reach the building.
i reproduced this several times just to make sure. i can't say if the same happens if you solve the Regis part of the quest by discrediting Karl infront of Papa Khan, the slave ledger definitely does it.

now i know this is not a fix but it might save you guys some grief. after 6 hours of loading, re-loading, crashing, searching the web etc. this killed a lot of immersion for me in an otherwise superbly fun game.

dear folks at bethesda/obsidian: please fix this.

AND FINALLY RELEASE INFORMATION ON THE NEXT FALLOUT!