GTA IV lag on powerful laptop

Solution 1:

Without lowering your graphics

Right-click on GTA 4 in Steam, and click on Properties.
Click on Set Launch Options... and a window with a TextBox will appear.

In that TextBox, paste these arguments:

-nomemrestrict -norestrictions

and GTA 4 should run with a huge speedup.
On my rig

i7 3770K
32 GB RAM
GeForce GTX 680

GTA used to run on max settings at around 20-35 FPS.
With these arguments, it runs between 50 and 55 FPS and averages at ~52 FPS.

With lowering your graphics

Interestingly, GTA doesn't seem to care about GPU so much, as there is almost no difference between playing with a 1920x1080 or 800x600 resolution.
The only settings that seem to yield any significant increase in FPS is View Distance and Detail Distance, which should be lowered together. With both set to 1, my max FPS went from 55 to 140, although the average FPS only increased from 52 to 55. I wouldn't recommend setting them both to 1, as it can introduce some odd graphical glitches, such as signs seemingly floating in midair, until you get close enough for the sign's support to pop into view.
You might want to set the ingame option Definition: On, which will deactivate Motion Blur (yes, On == deactivate) and earn you an additional 5-20 FPS when driving fast enough for aforementioned Motion Blur to kick in.

About why GTA fails to start

According to this wiki the problem may be caused by an out-of-date GFWL client, or because of your MTU size.

Solution 2:

Grand Theft Auto IV had an awful lag that was fixed in a patch. Make sure it is up to date. I had the same issue ages ago and updating fixed it nicely. Hope this helps!

Solution 3:

Are you sure you are launching the game using you Nvidia Video card and not your on board laptop card?

Find the .exe that you are launching. Right click on and there should be an option open with Nvidia card.

Solution 4:

I found a solution on this youtubevid: