Please don't delete this might be usefull for others!
THIS IS ONLY FOR NVIDA GRAPHIC CARDS(Doesn't work well on ATI, sometimes it doesn't work at all!)
Make sure u have the latest patches installed for gta iv and social club.... The best patch in my opinion that works best is the 1.0.3.0.
NOTE:This may or may not work for u, depending on how old or fast your pc is, it worked for me went up 17fps!!WARNING: DO STEP 3 AT YOUR OWN RISK!! IF U STOP IT OR U DO IT WRONG ILL PROBABLY WON'T SCREW THE GAME UP BUT JUST IN CASE FOLLOW IT CAREFULLY!!!!

For 7 series:
Haven't tested on the oldest ones but it did show improvement on the 7900!
For 8 series:
8400gt, 8500gt, 8600gt 256mb-1GB
For 9 series:
9400gt, 9500gt, 9600gt 256mb-512MB ONLY!
Those are the cards that have more trouble playing GTA IV, but luckly there is a solution without overclocking your graphics card! Since my gamming pc isn't fully done i decided to look for a solution for my 8500gt, the game lagged like crazy, i was getting around 19-21 fps on all low and on high around 5-9 fps!! Even though some people can play the game, getting an average of 27-32 fps on the graphic cards listed above, it did show an improvement form 32 to 46fps!! At the end When i finished I ran the game and from 21fps im getting an average of 32 fps!!!(30-32 on the outside and 32-40 on interiors!)
I dont have a verry fast pc or a verry slow one here is my pc:
PC:Gateway GT4022
Processor:AMD Athlon 64 @ 2.41GHz Performance rated at 4.0HGz
Ram:1.50 GB of ram (DDR)
Hard Drive 200GB
Video card: GeForce 8500gt
As u can see my PC isn't fast or slow.
Follow this steps CAREFULLY!1. Firs download this...
http://www.4shared.com/file/116004096/db2708dc/commandline.html its a command txt file. Place it in the game directory and don't eddit the file!!. For example: C:\Program Files\Rockstar Games\Grand Theft Auto IV
2. Once the command file is in the game directory, download this other one..
http://rapidshare.com/files/186766678/gtxd.rar and place it here C:\Program Files\Rockstar Games\Grand Theft Auto IV\pc\data\cdimages DON'T FORGET TO MAKE A BACKUP!!
Here get's complicated.........3. Download this other file....
http://www.4shared.com/file/116004163/2d178aab/Contig.htmlPay attention most get this wrong! Extract the Contig file cut or copy the contig.exe to the game directory C:\Program Files\Rockstar Games\Grand Theft Auto IV and make a shorcut to the desktop should look like this...

after u have the shorcut right click it and go to properties...on TARGET add a SPACE at the end then -s like this...

then click apply or OK. On the contig shorcut on your desktop run it u should get a CMD box and it should be done in 5-10 mins depending on your computer. Its verry importand that u dont stop it u should let it finish.
4. The last thing you are going to do is get hacked Nvida drivers(new ones) it seemed that the drives were locking the FPS at 19-22!!! with hacked drives the fps are free and unlocked meaning that there are no restrictions!! u can download it here, just chose your graphics card series or model and download your driver!!!
http://downloads.guru3d.com/Hope this helped.. It did for me i gained 17 FPS!!! If u need any help please leave a comment!

And yes it will help boost your FPS if u just want more performance!!!!!
Here is a pic getting 42 FPS without blurr on a geforce 8500gt!!!!!

Graphic stings: Almost high, little better than medium graphics!

And remember to mess around with the graphc settings for me on low settings it lags but on higher setting it doesn't lag! IDK...
AND ONCE AGAIN IF U NEED HELP LEAVE COMMENT AND ILL ANSWER..
UPDATEIve noticed that people are having trouble finding the video drivers so here there are:
For Windows XP (64bit & 32bit) http://downloads.guru3d.com/Videocards---NVIDIA-GeForce-(XP-32-bit)_c10.html Here is a direct link for the drivers for XP
32bit, choose the drivers that are more updated like "185.20" << just an example
http://downloads.guru3d.com/Videocards---NVIDIA-GeForce-(XP-64-bit)_c28.html Here is a direct link for the drivers for XP
64bit, choose the drivers that are more updated like "185.20" << just an example
For Windows Vista and 7(64bit & 32bit) http://downloads.guru3d.com/Videocards---NVIDIA-GeForce--Vista-%7C-7_c32.html Here is a direct link fo rthe drivers for
Vista and Windows 7, choose the drivers that match with your pc. Here the drives for Vista 32-64bit are mixed with windows 7 so be carefull read everything before you download.