GTA IV weird performance

Here's a couple of things, I don't know if it'll help but it's worth a shot:


the main problem with pc games compared to consoles is background tasks..... were a console will have nearlly zero background tasks a pc can have several and this can affect the performance and frame rate of the game
one of the biggest culprits are anti-virus programs... if these start up while gaming this can affect the frame rate and its not unknown for frame rates to drop like yours...... however some anti-virus software vendors have introduced gaming versions of their anti-virus software which wont run any scans or updates while your gaming.... and one such anti-virus is made by "eset"( http://www.eset.com/us/home/gamers ) ... this allows you to optimize your anti-virus to meet your gaming needs.....
you will also find information inside every pc game manual regarding background tasks and how they may affect your gaming experience... however you shouldnt go disabling any program without making sure its safe to do so .....
other causes of frame rate drop could be
1) new driver needed.... however in my experience when you find a video driver that works well you keep it.... downloading and installing the latest driver can in some cases reduce performance....
2)direct x .... allthough a intergral part of any pc game the direct x runtime files needed for the game will be installed during the game installation so adding any future direct x files wont improve the game
3) power .... if your psu isnt delivering enough power to your graphic card then some cards will throttle back the core/memory clock speeds to allow for the reduced power.... however this would be hard to diagnose.... you may want to check the psu using a voltage meter and ensure its delivering the advetised wattages.... if its a budget psu then it may be delivering lower wattages and this can happen at any time without warning
however im sure the reason for the low frame rates is something innocent .... however run a security scan (anti-virus and anti-spyware ) ...... then check other games to see if they are affected....
finally graphic cards can become faulty.. however this would involve artifacts and visual defects.....
good luck

2. Fraps takes a lot of resources when recording, so you can't get a good FPS count.
If you want to get a higher FPS, try Bandicam.
Bandicam compresses the recording video when recording, and uses much lower CPU/GPU/RAM usage than Fraps. As a result, you may get better frame rates.

GTA IV is a known terrible console port. It doesnt run great,on anything.

Yeah after looking around I couldn't find a fix. Try downloading a recorder like fraps or bandicam.