Left 4 Dead 2 FPS Problems

[VagelisZampras]

Hello guys I own a Asus K750JB-TY014H laptop with the following specs:

Intel Core i7-4700HQ cpu 4-core 2.4 GHz
Nvidia GeForce GT740M 2GB Graphics Card
8GB (7.89 Available) RAM Memory (DDR-3 I believe)
2 * 1TB Mechanical HDD
17.3" HD 1600x900 LCD Screen

The problem is specifically about Left 4 Dead 2. I always had problems with this game and it gets irritating because I am a big fan. Anyway when I open up the game and load a map, the FPS is perfectly playable (100+ at medium-low settings and 1280x720). But after 5-10 minutes the FPS drops and stays around 50-65. I understand that this is also good enough, but why not get 100+ fps at the current settings, as my machine has proved to be able to handle that? Note also I have tried different launch options and resolutions and problem still persists. And it doesn't happen on csgo or other valve's games either. (I can get 70 FPS stable on csgo with medium-low settings).
Alt+Tab out of the game seems to fix it for a minute, then FPS drops again. Problem occurs while using only one script (Kaizen's Performance Script or whatever it's called) and both on singleplayer and also multiplayer. Pls help I really love the game!

 

[migronesien]

Probably because the cooling inside a laptop isn't that good. Your hardware might run a bit hot after like 10 minutes and then slows down a little bit to prevent overheating. That's pretty common with laptops as far as my own experience goes.

 

[VagelisZampras]

I don't think it's cooling. I use a cooler pad and also the laptop is running MUCH cooler than it does when running other games (where you could cook eggs on it)