It's still Windows, so it will need housekeeping regularly.
CC Cleaner
Defrag
Remove unwanted programs + any bloatware the Dell installed from new
Run MS config & work out what you do & do not want to run at startup, last time my toshiba lappy slowed up noticeably, I found something like 20 odd programs all helping themselves at startup from Acronis true image to adobe reader. If you don't need them, kick them out.