HELP!!! Laptop lose performance during working to (-80%)

I have Dell Latitude E6320 : i7 2640M ,8GB Ram , Intel hd 3000, 300GB HDD .
When im playing or using google or when i change brightnes my laptop like drop fps to 01 , i play cs go with 20-30 fps when the DROP it happen the cs go fps drop to 01 , laptop works sloww to sloww ? idk why , then when i restart it start good , than again it happen the (fps drop on laptop ) ?? HELP
this making me restart my laptop every 20-30 min cuz fps drop ? i did some fresh restart , clean up , max perfomance on (POWER) then advanced settings on windows settings . but nahting changed !