The Bees swatted Gary Rowett's men aside, with Lasse Vibe and Jota both hitting braces in an emphatic win that all-but ends Derby's hopes of a top-six finish.
The hosts' goalscorers proved to be a constant menace and Derby struggled to find a response to Brentford's free-flowing football.
Smith, who was appointed in November 2015, is adamant any team who attempts to take his players on does so at the risk of a damaging defeat due to the attacking options he possesses.
"It's a very good result and maybe one of the best performances since I've been here with the calibre of opposition and the form they've been in," Smith insisted.
"I thought we coped with what they had. I must admit I was quite pleased when the second goal went in. It calmed us down and I thought that was game over.
"Defensively our structure was really good and we made it very difficult.
"Derby had to come at us to maintain their play-off challenge but any team who comes at and wants to have a football game can be on the receiving end of a result like that," he added.
Today's result moves the west Londoners up to 11th place in the table and although a late surge towards the play-offs may be beyond Smith's side performances such as this suggest a promotion push could be on the cards next season.
But the 46-year-old is reluctant to put too much emphasis on future targets and is keen for his squad to be allowed to mature.
"It's a very tough league to get out of. You only have to look at some of the teams who won't go up this season - there will be some big ones," Smith said of the competitive second tier.
"We're a young group and we're emerging. We've got the likes of Daniel Bentley, Romaine Sawyers and Rico Henry - those three guys haven't played in the Championship before.
"The squad has got better - we've got some depth there. I can look over my shoulder in the dug-out and know I can affect the game."