The game turned just before half-time as Shefki Kuqi and Tommy Miller nettedand Town maintained their superiority after the break, adding a third through Darren Bent.
Preston haven't scored at Portman Road for over 40 years, and although they threatened at times, they mustered only two efforts on target all game.
Preston threatened first when Paul McKenna fired narrowly over before Kuqi rounded visiting keeper Gavin Ward and laid the ball back for Ian Westlake, whose firm drive was cleared off the line by John Curtis.
Replays suggested it may have crossed the line, but it was a borderline call. Soon after Ward did well to tip over a Bent drive and when the keeper denied the same player again, the loose ball was fired on to the post by Kuqi.
Town continued to carry the greater threat and they made a double breakthrough in the dying moments of the first half.
First Kuqi beat Chris Lucketti, with a hint of handball, to collect a Jim Magilton pass and run on to drill a shot under Ward, before Kuqi's flick found Bent whose low cross was firmly driven low past the Preston keeper.
Town lost a 2-0 lead to draw at Watford last week but seemed determined not to make the same mistake again, starting the second half on top as Magilton, Fabian Wilnis and Kuqi all shot over.
Guylain Ndumbu-Nsungu dived to head home a McKenna cross on 53 minutes, but was flagged offside as Preston enjoyed a decent spell of pressure, during which Lewis Price turned a Dickson Etuhu shot from an Eddie Lewis cross onto the post and behind.
After that the home side carried the greater threat, and it was just a case of how many more goals Ipswich would get, as they repeatedly attacked on the break.
One such break on 72 minutes saw a clever Kuqi back-heel free Westlake who swept the ball wide for Bent to lash a shot home from the edge of the area to make it 3-0.
Preston did have one more great chance late on as Jason De Vos failed to cut out a loose ball, leaving Etuhu free on the edge of the area, but he curled his shot wide of the target.
The only downside for Ipswich was that both Miller and Wilnis went off with injuries which must make them doubtful for Tuesday's home clash with fellow promotion hopefuls Sheffield United.