No, no, no. I mean save in the background to remove the save delay. F3 and F:NV experience no saving pause. With Oblivion, when you save, the game freezes for a couple of seconds with heavily modded games.
Not for me it doesn't. Case by case, perhaps?
And have you modded FO3 and/or FONV to the same extent as the Oblivion you're talking about there, and in (more or less) the same ways?
If not, you might find, with the hardware you're using, the same thing would happen with those games. Makes sense, really. Saving is saving, regardless. At some stage, something actually has to written to the HDD. There's no getting around that. And if that's going to take a while, for whatever reason(s), well...