Many or most laptops are very prone to getting dust buildup internally that partially blocks the air flow critical for the cooling of the CPU and RAM, etc. So that is, I would say, the most likely explanation for what you describe. Even when the CPU is just idling it does get quite warm and in your case I would guess the fan is struggling to keep the CPU and laptop internal temperatures in acceptable ranges. About the only easy way to pull that dust out of the system, as far as I know, is to apply a little vacuum to the fan output grid; as far as I know the output opening is always on one side edge of the laptop, often towards the back. I would suggest that you install a CPU temperature measuring utility such as "Core Temp", the first that popped up in an Internet search I did and I believe free for personal use. There are other utilities like it. You may be able to get that temperature value by booting the laptop into its firmware; many have a "Monitor" section. You would want to run the machine for a while to get it fully warmed up and then reboot to "Settings".