My Acer Swift SF315-52 is Heating up very fast.

1. Check the power settings. Settings > System > Power & Sleep > Additional Power Settings. Make sure the power profile is set to Acer. 
2. Check the battery settings right below Power & Sleep. Battery Saver should be set to off. 
3. Click on the battery icon in the system tray. This should be set to "balanced" or "best battery." If it's set to "best performance," there is your heating problem right there.
4. Now go to Start and type "AMD" then click on the AMD Radeon app that comes up in the search results. 
5. If it shows a wizard for quick setup, just click Skip.
6. Click on Gaming > the settings gear in the top right corner > Graphics. This should be set to Standard.
7. Click on Display, which is on the right of the Graphics menu option. 
8. Virtual res and GPU scaling should be turned off. The scaling mode should preserve the aspect ratio.

If all of this checks out fine, start looking for what program or programs are keeping the system so busy. When it starts getting hot, hit Ctrl+Alt+Delete, select Task Manager, click more details, then click on the CPU column to bring all the apps using the most CPU to the top. Most apps use a max of 5-7% of the CPU in idle. You can either disable any offending apps or you can give them a different priority. Everything has normal priority by default. If you change the priority to below normal, it means all other apps with normal or higher priorities will be prioritized over the apps that are set to below normal priority. Individual application priorities can be set by right-clicking on the app and going to Set Priority.

Normally I would recommend digging into background services as well, but assuming you're using the Windows defaults, that shouldn't be causing it. 

Depending on the age and past usage, you may need to take some canned air and clean out the air vents. Also feel along the backside where the screen hinges on... there's an exhaust vent that's cleverly built into the hinge. Make sure it's pushing air out. If you don't feel anything blowing air, you probably need the exhaust fan replaced. Normally, though, the BIOS will warn you at boot if the exhaust fan isn't functioning. 

There is a solid 95% chance that a program or inappropriate setting somewhere (or several) is causing all the extra work. Also, it would help to know what antivirus software you're using as not everything is going to run well on an ultrabook. The best performing security software options are cloud-based. Additionally, an antivirus does little good nowadays without a firewall or VPN to back it up. Running an antivirus by itself without a firewall or VPN is like setting up a security system for your house but leaving the doors and windows unlocked. Sure, the system will go off once the thief is in there, but it's better to keep them from getting inside in the first place!