This message was posted on behalf of Intel Corporation
Hi, Brunno_Neves, Thank you very much for joining the Intel® Processors communities and for providing those pictures.
In regard to your inquiry, normally the laptop should work the other way around, it should provide more clock speed when the laptop is connected to the outlet than when you are using it in the battery mode. However, in order to find out why the notebook is showing this kind of behavior, the best thing to do will be to get in contact with the manufacturer of it, since they build it they should be able to provide all the information in regard to performance depending on the power source that is being used:
Contact Dell Support | Dell US
Any further questions, please let me know.