Hoops manager Neil Lennon was looking for one big effort from his players before they fly out to Turkey on Monday for a winter break - albeit they are scheduled to play two games in the Antalya Cup, a tournament which also involves Galatasaray, Trabzonspor and Dutch champions Ajax.
And he got the performance he wanted against a Saints side who battled hard but who were ultimately outclassed.
Striker Anthony Stokes grabbed a second in the 58th minute before Commons grabbed a quickfire brace as the Hoops extended their unbeaten league run to 20 games on their march towards the title.
Lennon, who replaced striker Teemu Pukki with Stokes in the one change to his side, had asked for "a little more zest" following three mostly lifeless 1-0 wins.
However, it was a low-key start to the match with the early kick-off not helping the atmosphere.
The visitors had the first real chance of the game in the 25th minute when Commons cleverly played in Mulgrew at the edge of the box but although the Scotland international beat Marian Kello with his shot from 12 yards, the ball bounced off the post and somewhat fortuitously back into the arms of the goalkeeper.
The Buddies enjoyed some more luck in the 31st minute when Commons' wonderful chip from 25 yards beat Kello but came off the post with referee John Beaton awarding a corner, although it did not look as if the keeper had got a touch to the ball.
The idea that the first half was destined to be goalless was confirmed four minutes from the break when Commons ended a Hoops attack by heading an Emilio Izaguirre cross from the left over the bar.
The second half began quietly before the visitors took the lead.
Celtic right-back Adam Matthews burrowed his way into the St Mirren penalty area with little resistance from the St Mirren defenders before flicking the ball to Mulgrew to steer into the far corner from 10 yards.
Celtic's second came six minutes later when Joe Ledley picked out Stokes in the box for the Republic of Ireland striker to guide his shot past Kello and into the far corner of the net.
That was the contest effectively over.
The champions were in complete control and Kello made two fine fingertip saves, the first from Celtic skipper Scott Brown and then from Stokes, both at the expense of corners which came to nothing.
However, Celtic were not to be denied a third and it came when Commons stooped at the back post to head in an Izaguirre cross.
Two minutes later, the former Derby and Nottingham Forest player made it 4-0 when he slammed a cut-back from James Forrest high into the net from six yards, giving the hapless Kello no chance.
It became a case of how many more the Parkhead side would score and Commons came close to getting his third in the 78th minute with a low drive which was on its way to goal before it was deflected wide.
Stokes then fired just over the bar from distance before Saints defender Darren McGregor got a last-gasp tackle in to thwart Hoops substitute Amido Balde, who had replaced Forrest, but there were to be no more goals.
- Sports & Recreation
- Charlie Mulgrew
- Anthony Stokes
- Marian Kello