Computer over heating issues, fan replacement and now fps drop across ALL games

Hello,

So my laptops fan became faulty and did not start along with the computer. I took it in for a replacement which went well. After i got it back, for some reason the new fan would still let the laptop reach 70-80 degrees after half an hour to an hour of gaming so i returned it to the computer shop to check.

Now, receiving it back, the laptop runs A BIT cooler however i have fps drops across all games. I even recieve mini lags when browsing the internet and my fan is much louder than before.

I can deal with the mini lags but the fps drops to around 9-15 and makes everything unplayable.

does anyone have any solutions for me?

thanks a lot