First-half goals from Paul Hall, Wayne Allison and Caleb Folan ended the match as a contest and Hall and Allison added further goals before Millwall pulled one back late on.
This was a quite dreadful display from Nigel Spackman's new-look team, but the fact that the players have only been together for a short time cannot excuse the basic errors that were made.
The first goal was a disaster for Richard Shaw and Zak Whitbread who both had opportunities to clear the ball before Hall scored with a well-placed right-foot shot from 12 yards.
The second was another horror show for the Millwall defence when they failed to cope with a routine cross from the left and Allison was left unmarked to score from eight yards.
Folan took his goal coolly but he was allowed to run through a static defence to beat Lenny Pidgeley for the third time.
Spackman went to a back three in the second half but the defending was equally inept and Hall was left with yards of space to place a shot from the edge of the area inside Pidgley's right-hand post.
Worse was to follow in the 65th minute when a free-kick from the left saw Aaron Downes unmarked at the back post and, although Pidgeley blocked his header, Allison bundled in the rebound.
By now a large number of fans had already headed for home after booing their team off the field at half-time and they missed the only highlight of the afternoon for the South Londoners.
Substitute Kevin Braniff pounced when Derek Niven slipped and his well-struck right-foot shot found the bottom corner but it was a goal that hardly mattered.