Here my specs:

Pentium Dual Core T-4200 @ 2.0 GHz
3 GB Ram
Windows Vista
ATI Radeon 4500 video card

My laptop can run Fallout 3 on medium settings with a decent FPS. But this new game my FPS is pretty bad. I don't get this, isn't this practically the same game?

To the OP, it's because there are little tiny graphical upgrades here and there, not to mention the size of New Vegas's map is a pretty good amount larger than Fallout 3's.

Try updating your drivers if you haven't already, or making sure you're on the latest patch. The latest patch helps TONS with performance issues.

Also, with as much RAM as you have, make sure you're not running anything that's too memory intensive in the background while playing New Vegas. Vista on idle usually uses up 1 GB of RAM, so you really only have about 2 GB or less of RAM for New Vegas to utilize. Close IM clients and the like.

Well, it is the same engine, but there are a lot of things that could change the FPS.
You could try to optimize some settings. Here is a link with some of the tweaks you could try: http://segmentnext.com/2010/11/02/fallout-new-vegas-tweak-guide/
Some people have no problem anymore since the last patch, but some still have terrible FPS.
Since you have an ATI card, you could try the ATI dll: http://www.newvegasnexus.com/downloads/file.php?id=34970

I think it's been confirmed that the new patch breaks the old .dll fixes, so these are now obsolete unless your version is older than 1.2.0.285.

I know that the new patch might break the dll and I know that there is a note on nexus saying: "Note: After the 2010/11/9 patches, this fix might be obsolete. Make sure your game is patched, and see if this makes it run better or not."
But I thought that I saw some people on the forums saying that it still helps them.
There is no harm in trying it and if it does help, nice. If it doesn't to bad.

To start with, I really cannot agree that a system as weak as the one described actually does much of anything on "Medium" and is doing so with good resolution settings. Laptops are a poor choice to game on, and are unsupported, because they adhere to no particular standards, in spite of the reference examples offered by the GPU chips' designers. When it was new, the HD 45n0 Radeons for desktops were borderline products only, sitting at the top of the business graphics class, but trailing the HD 4650 by a very wide margin, and that was two years ago.

Although someone once disagreed that the tendency of a couple of years ago for the typical laptop graphics card version to trail its desktop kin by at least 10%, and frequently 30% of performance is supposedly less true than it was, no benchmarked examples were included, so that I'm unconvinced that there's been much of a change.

The Pentium Dual CPUs may have been descendants of the Core designs, but the Cores have a ton of onboard cache, while the Pentium Dual lost almost all of its cache on its way to becoming just another Celeron equivalent.

Hmmm? There's no conclusion to what I wrote. Until this edit, anyway, there wasn't.

IMO, Fallout 3 and that system were at best a Low Quality matchup. There has been a minor amount of added demand from the older game to its sequel, as well as the breakage of the connection that the game is supposed to make between Dx9 and the newer Dx10 capable graphics hardware. I think that this pushed the laptop you have over the edge of the performance precipice.


Gorath