Adebayo Akinfenwa bagged a goal in each half, the second coming from the penalty spot, to move to 12 for the season .
Chris Hackett added a third goal before Joel Grant reduced the arrears from the penalty spot for a Wycombe team that held their own for long periods but slipped to the bottom of the table.
Boothroyd said: "I was pleased with our first half performance, we dominated the game and deserved to be a couple of goals up, but not our second half display. We made some daft decisions on the ball in the second half and we looked mentally tired at the end.
"Obviously, I'm pleased we've got the three points but I've told the players that the second half performance wasn't good enough. On another day that would have ended up a draw if we hadn't been so clinical in front of goal.
"We've had some long trips recently but I can't use that as an excuse, it's the same for all clubs in this league. At least we dug in, weathered the storm and got the result.