Right clock on the task manager cpu graph to see the logical processors.
What might have changed since all was well a day ago?
Consider using system restore to reset back to a previous time when all was good.
I see many complaints about gaming laptops not performing well.
Usually gaming while plugged in.
One common cause is thermal throttling.
Laptop coolers must, of necessity be small and light.
The coolers are also relatively underpowered.
If you run an app such as HWMonitor or HWinfo, you will get the current, minimum, and maximum cpu temperatures.
For intel processors, if you see a max of 100c. it means you have throttled.
The cpu will lower it's multiplier and power draw to protect itself
until the situation reverses.
At a lower multiplier, your cpu usage may well be at 100%
What can you do?
First, see that your cooler airways are clear and that the cooler fan is spinning.
Use a windows balanced power profile, not the performance profile.
Set a minimum cpu performance to something like 20%
It is counter-intuitive, but, try changing the windows balanced power profile advanced functions to a max of 90% instead of the default of 100%
You may not notice the reduced cpu performance.