I had the same problem a while ago, and I solved it with thses Utilities:

Links:
Tune Up Utilities 2014
Glary Utilities
IObit SystemCare

Once installed, just click on the option "Turbo", then you decide if you want quality or performance. With this program my fps went from 20-25 to 40-60.


Also low down your FX quality and same for resultion.

Go to /settings and make your draw flip distance (if I typed it right cause I don't remember the name well) and set it on 320

Download Razer game booster, It may give some boost.
Also check this topic it may help you alot.

Try To low you GTA/MTA Graphic and make them like this:

(Like me, it helped )
Try those steps it may help you (Ingame):

1) Go to /settings and disable "CITy texture". CITy texture option in /settings was removed. Try the other solutions below.
2) Search on "Max distance" and change the value to 300.
3) Go to the server Textures part, and toggle all texture mods off.
4) Go to ESC > settings > advanved and toggle the video textures ("Streaming memory") off
also Remove all your mods cause it low your FPS and Set your router to dynamic ip mode.
Download CCleaner: http://www.fileparade.com/listing/121963/CCleaner?did=10844&pid=1&ppd=search,36199504122,ccleaner,e,,c,0,,,&gclid=CLup5vu9wb0CFWT4wgodA3EAZw To clean Your PC.

you can fix this problem by replacing the files in your GTA these files will remove the smoke, flares and everything else, which would make your fps drop you can find the files below.

Link:

-Use the GTA SA shrinker to shrink the images of gta3.img
-Replace the files in models with the one in the models folder in GTA folder.
-You can use the fps tweak to lower the draw distance and quality.
-Use the black timecyc to make your sky black and will make your fps more stable.