Thank you for your message. I apologize for the inconvenience caused. I will be glad to assist you with this.
Please run a hardware diagnostic by following the video on this link & check if there is an error.
Is the system slow from the time you start the computer or is it slow when using any application?
For my reference, please click on the message tab next to your avatar– click “New Message” & search for my Dell username (Sreejith R) & send a private message with the service tag, registered name & email address.