Rob Horne registered a first-half double to help Saints secure a bonus-point 40-25 win against London Irish at the Madejski Stadium on Sunday afternoon.
Nic Groom, Mike Haywood, George North and Cobus Reinach also got on the scoresheet as Jim Mallinder's men made it three wins in a row in the Aviva Premiership.
London Irish struggled to cope with Saints' attacking intensity as they suffered their third successive defeat.
Horne hogged the spotlight in the first period, scoring his first and second tries for the Northampton first team, having arrived from Super Rugby side the Waratahs this summer.
But it was a fine all-round team showing from Mallinder's men in the first period as they produced a razor-sharp attacking display that their hosts couldn't live with.
Saints started the game with what will be a try of the season contender as a quick counter-attack from inside their own half eventually finished with Groom dotting down.
It was an eye-catching moment for the away side and the conversion was added by Harry Mallinder to secure a 7-0 lead.
And it wasn't long before Irish were cut apart again as Horne found the space and speed needed to dive over for his first Saints try under the posts.
Mallinder again added the easy extras to put his team 14-0 up inside the opening 10 minutes, and Irish desperately needed a rapid response.
They were able to put some pressure on after going to the corner, eventually earning a kickable penalty, which Tommy Bell landed.
Irish were growing into the game, but they were struggling in defence, with Saints' power game proving too much.
And after Courtney Lawes started a move by shrugging off a defender, Horne got hold of the ball and held off what seemed like half of the home team as he forced his way over the line.
Mallinder missed the conversion, but Saints were already seeking a try bonus point, looking menacing every time they entered Irish territory.
The away side kicked for the corner in pursuit of a fourth score before the break and from an inexorable lineout drive, last season's top scorer, Haywood, dotted down.
Mallinder kicked to make it 26-3 and Irish almost looked out on their feet, such was the intensity of the Saints play.
Irish did register another penalty, via the boot of Bell, on the stroke of half-time, but they had a huge amount of work to do in the second period at 26-6 down.
Alex Lewington helped them to eat into Saints' lead as some poor defending out wide allowed the wing to find his way to the line.
Bell added the extras to cut the gap to 13 points, but Saints were soon straight back at the Irish door and, with the penalty coming, the ball was sent wide to North, who scored.
Mallinder landed the tricky conversion before Saints were given a let-off as Luther Burrell's pass was intercepted by James Marshall, who stumbled as he tried to reach the line.
Irish continued to give it their all and Saints suffered an injury blow as Burrell limped off with 15 minutes to go.
And the home side scored soon after as the pressure was applied close to the posts before the ball went wide for Bell to score.
The conversion was missed, leaving the gap at 15 points, and Saints needed a fantastic tap tackle from replacement scrum-half Reinach to stop another Irish attack.
Reinach was in action at the other end before time was up as the South African broke free from a counter-attack and scored his first Saints try.
Mallinder converted to put the icing on the cake, but Irish had the final say as Josh McNally dived over and the try was awarded by the television match official.
London Irish: Bell; Lewington, Tikoirotuma, Williams, Nalaga (Ojo 71); Marshall, McKibbin (Steele 51); Franks (c), Porecki (Paice 46), Du Plessis (Hoskins 58); van der Merwe (Paulo 58), De Chaves; McNally, Gilsenan (Schatz 62), Cowan.
Saints: Tuala (Foden 60); North, Horne, Burrell (Grayson 65), Collins; Mallinder, Groom (Reinach 60); Waller (Ma'afu 62), Haywood (Marshall 75), Hill (Brookes 57); Paterson, Ribbans (Day 62); Lawes (c), Gibson, Dickinson (Nutley 67).
Referee: Matthew Carley