Guild Wars 2

As title says, this issue of mine keeps coming back and I dont know why. The problem is that usually when I start playing everything seems normal with almost 70 fps but after couple of minutes fps starts dropping to little over 20 for about 2 seconds and then goes up again to normal for 5 seconds and drops again and the cycle repeats itself over and over again. I have tried messing with graphics options as well as my pc options but nothing fixes it. It might be that my pc is couple years old and surely has outstayed its welcome but I need to know if there are other options than to ditch this expensive laptop of mine and get a new one. List of specs:

Asus Notebook G74Sx Series
Intel® Core™ i7-2630QM CPU @ 2.00GHz 2.00 GHz
(RAM) 8,00 Gt
64 bit

Sounds like thermal overheating throttling the system clocks back.

use cpu z to monitor your cpu and find out if it is overheating,

i suspect the same thing as everyone above your laptops is old enough for the thermal paste to dry up. It doesnt look too difficult but there is quite a lot of screws