Game suddenly very slow and laggy

It's fine, I'm more comfortable with English. The only apps that are running slow are my default Windows 10 apps. Like Microsoft Edge (which doesn't load anything at all) or Store. I can't really summarize it by just saying that they're all "running slow" because there are apps that don't load at all, there are some that work fine and some where it's fine most of the time, but then some weird error would pop up. But I didn't notice anything weird with my other apps, so I just assume that it's only the case for default apps.

Yes, that was the report.

I think it's just Microsoft Apps in general. For example my Netflix app is very slow and laggy too. I think it's just weird that Sims 4 is somehow affected if it really is the same issue that's causing all this. I have tons of other games and not a single problem with them.

@8ochinchin 

Do you monitor the temperatures of your hardware?

Edit: Ok, @puzzlezaddict  already took care of that... 😳

I need to see what is going on at your system:

• Download and run hwinfo (The green field, not the red one! [download for free])
  
• Click on sensors only > click on the sheet with the green cross (logging) > give the file a name and save it.
• Wait 5 minute > Play The Sims for about 10 minutes.
• Stop the logging of hwinfo64 (Click on the sheet again) > upload the log file to a free file hosting side (onedrive or dropbox for example) > post the link here.

Also report any issues while running the test.

Here it is. Pretty much all the same, very slow, very low framerate, other than that - perfectly functional, all game mechanics work. 

https://1drv.ms/u/s!Am5yxC8GBEgqaUTmD1SXshskA8E

Okay, so there is an issue. My computer is basically new. I mean, not really new, but new enough for me to be able to say that if it overheats easily, then it's the computers fault and not the dusts. The max temp for my computer should be around 95°C (for the CPU, it's lower for the GPU), then it throttles. The computer's good, but if you don't use a cooling pad the CPU will melt into hot lava within 2 minutes. I quickly used the Predator Sense app and my CPU is currently at 62° which is basically nothing with this thing, but it's clearly throttling anyway. While playing the temperature usually reaches 75-80° (at leasts that's what the app is showing me) and if it goes above 90 I let it cool off for some time. Getting it below 60°, especially while playing would be physically impossible. It's that it really shouldn't throttle at below 90-95° anyway is what's bothering me. I know that cleaning can't make the situation worse and that I should clean it and even if it doesn't help, it's not like I did something bad, but that means disassembling it and uhhhhhh I'm not sure if I want to do that unless I know for a fact that it's necessary. Just getting the instruments to unscrew the case is a pain in the *ss, then there's the neverending anxiety that my sinful hands will break something.

@8ochinchin 

Fully understandably.

If you are not comfortable to open it you can use a vacuum-cleaner like shown in this video. 

That is not ideal, but it can make a difference. You should try and test afterwards.

If that don't helps you could look at professional help in your region. (Where did you purchased this Notebook) The problem with this is that you might lose warranty, and if the Notebook still has warranty it might be better to use it.

It is true that your CPU should throttle at around 95°, and it is also true that it is normal that the components get a bit warmer in a notebook as in a desktop computer.
But the temperatures your Notebook reaches are not normal at all, there is a clear problem with the cooling.

I can't say if this is a warranty aka defect components problem or a dust problem. I saw Notebooks developing a dust problem in a couple of weeks, and not because the environment was dirty but because a dust flake got stuck at the wrong place and dust then formed a "wall" that rendered the cooling nearly useless. 

(And this one was not the only one I saw in this condition, 🙂 you could not see this from the outside.)

So, all told, if you are absolutely sure that this is not a dust problem, or if the vacuum cleaning method don't make things better, and if the Notebook still has warranty, you should use it. (If it is a dust problem the vendor will probably charge you for the cleaning)
If there is no warranty and if the vacuum cleaning method don't make things better you should go to a computer shop in your region.