England head coach Stuart Lancaster said his side "lacked intensity" in their victory over Italy at Twickenham.
England recovered from conceding the first try to win 47-17 and keep their 100% Six Nations start intact.
But Lancaster said his young side, who beat Wales in Cardiff last Friday, started poorly, with Sergio Parisse crossing to give Italy a 5-0 lead.
"I am disappointed really. I thought we lacked the intensity we had in defence last week," said Lancaster.
"We addressed it in the second half but the last try was a frustrating one.
"I guess at the start of the day, if someone had said we would get 47 points, I would have taken it.
"We played some really good rugby and scored some excellent tries. Then defensively, apart from the last minute, we really fronted up physically."
England full-back Mike Brown had to be replaced in the first half after after appearing to be knocked out in an inadvertent collision with Andrea Masi, and will not take part in training this week ahead of the trip to Dublin to face Ireland on 1 March.
Lancaster says England will follow all the return to play protocols when monitoring Brown's condition.
"We will see how he goes the following week before deciding whether to pick him for Ireland," added Lancaster.
"I saw him after the game and he seemed fine, if a bit grumpy because he had to miss most of the game."
Ex-Ireland wing Denis Hickie on concussion:
"Players could come off in the past having not remembered the last part of the game. That no longer happens.
"The protocol, analysis and treatment of blows to the head is different, it is far less arbitrary. I don't doubt that the medical procedures and protocol - while evolving - are much better."
Fly-half George Ford added 15 points with the boot, while Bath team-mate Jonathan Joseph crossed for two tries.
But Ford said England must improve ahead of their meeting with the 2014 champions, who defeated France 18-11 on Saturday.
Speaking on BBC Radio 5 live, the fly-half said: "We're delighted to get two wins out of two but we have lots of things to work on and it will be a hard game in Dublin.
"Playing with JJ week in, week out, I see it all the time, so for him to do it on the international stage is brilliant for him. If you give him the ball in a bit of space then he is lethal."
There were also tries for Billy Vunipola, Ben Youngs and replacement Danny Cipriani, while 36-year-old Nick Easter forced his way over to become the oldest England try-scorer of all time.
"The years are going to keep creeping up on me. I hope the tries do as well," said the Harlequins forward.