Laptop sometimes slow sometimes not?

I got a new laptop about 2 weeks ago because of the dell latitude e6540. I looked at neighbors with exactly the same laptop / system before, but now that I've tested a few games myself, my laptop does below average. For example in Rainbow six siege. Sometimes it runs at 60fps without problems, but most of the time it runs in the 10-30 fps range. I've observed that it always runs smoothly when the GPU goes over 60 °, but there seems to be some kind of limitation. Does anyone know why it is sometimes there and sometimes not? GPU: AMD HD 8790M GPU: i5 4210M overclocked to 3.1 GHz.

Did you always plug the laptop into the power supply? This usually makes a big difference in performance with laptops.

Shouldn't you know that you can't really gamble with such hardware? Turn everything down and connect it to electricity. Then it could go.

Yes is always connected to electricity, regardless of whether it runs smoothly or not.

Yes, but as I said, the laptop is enough for 60 fps on low settings. It's just a matter of luck whether the performance is limited or not.

Sorry, the notebook is bad.

Your CPU is a 7 year old DualCore CPU and your "OC" is not an OC. The CPU clocks with a core in Turbo up to 3.2 GHz.

The same applies to the graphics unit. It has the approximate performance of a desktop version NVIDIA GT710.

That with the temperatures is actually more so that the clock is lowered if more than 75-80 ° are reached and thus the performance decreases even further.

In the sum of all things one has to say unfortunately… This notebook is not designed for gaming… Set everything to low and cool properly.

You can be satisfied that Rainbow six is running at all.

Is there a way to connect a desktop GPU to the notebook? Because I still have an old R9 270x lying around with me. Back then it ran with an I7 920, and rainbow ran smoothly. And the i7 ran at a maximum of 2.7 GHz

No, that doesn't make sense. There's no reasonable technical solution