Your laptop is literally a decade old seeing your specs. Chances are even if you somehow took the best care of it, the laptop needs service. If I were you I would repaste your CPU/Graphics chips since they are long since past dry causing thermal issues. I would also suggest you dust out your fans as well since they are probably inundated with dust. The entire internals could probably use a dusting out as well.
Finally if you really want to keep this thing going (lord only knows since this thing will only get worse over time) I would suggest replacing your hard drive with a SSD, check your ram to see if its still good since excessive heat buildup can cause ram to cook and die (same with HDD's), Replace your battery since its probably past the point of being useful and a lack of replacement could cause dangers in the long run. Also I would suggest start pricing a screen replacement eventually because while its rare its not impossible to see a screen die out after enough time.
Honestly Laptops these days typically have a 5 year lifespan before problems arise. If you are truely wanting to keep this around for longer than it should have its life to its going to be like taking care of a car that has 300,000+ miles on it. Expect hardware failures and be prepared to spend money to fix them until the system is no longer repairable.