Laptop Underperforming

[DunkExpress]

So I bought an ASUS ROG GL771J laptop in 2015 (stupid decision btw, if i knew then I could have just built a pc for insanely cheaper and it would be better), it has a Intel i7-4720HQ core @ 2.60 GHz and a Nvidia 960M graphics card. In the last year and a half/2 years it has come to undeperform a lot for these components (yes i know they are old, and nothing compared to nowadays components). For example, I used to play a lot of GTA, which is a demanding game nonetheless, and my pc could achieve a stable 60 fps with moderate to high video settings. However now I cant play this game, because with everything on minimum it runs at about 20 fps, and even if I lower the resolution, I have to lower it incredibly low for it to perform with decent frames. League of Legends is another game, that I used to play at pretty high fps, now I need to lower the quality for it to retain 60 fps. I know that components deteriorate over time and that they dont retain their full capability throughout their lifetime, but I feel like in 5 years is a relatively short period of time for the laptop to drop in performance like this, I literally cant play half of my steam library...Any tips or help would be greatly appreciated.

Useful information: All my drivers are up to date, I used driverBooster to do this, in exception to my GPU which I updated through NVIDIA Geforce experience. I have tried to overclock my GPU with MSI Afterburner but with no sizeable result. I have never cleaned my laptop but will in about 3 days with a friend of mine. I have monitored CPU and GPU usage for the past month and some overheating is present, hence why I will clean the fans and other components and most likely reapplying thermal paste. If you need any other information or specs feel free to ask.