Gareth Bale netted a hat-trick against the relegated Blades, with Son Heung-min adding a fourth to compound United’s misery as they suffered their 27th defeat in their 34 league matches so far this season.
United ended the game having had one shot on target, but a double change at half-time did see them improve a little – before Bale’s second goal took the wind out of their sales.
“It’s anger at the first-half performance,” Heckingbottom said.
“I didn’t enjoy watching that. It was a passive performance. There was a difference in the second half, in approach and attitude.
“From Spurs’ point of view they’ll be happy with the goals but we’re not.
“The first is so passive, the second is a counter from our corner and the third is a giveaway in a bad area.
“We know he [Bale] is a world class player bit we can’t afford to give that type of player those opportunities. We have to be at our best to compete at this level.”
It could have been worse for the Blades, as Son saw another strike ruled out for offside, while both Chris Basham and Sander Berge made their returns from injury.
“We know we’ve played against good players ever week in this league and we have to be at our best to compete, and we weren’t in the first half,” Heckingbottom added.
“That was the bit that upset me, to be honest. The first half wasn’t good enough.”