The Bees had five different goalscorers at Deepdale, Bryan Mbuemo opening the scoring from a low cross from the right before Marcus Forss did the same before half-time.
Ivan Toney made it 3-0 in the second half before Sergi Canos and Emiliano Marcondes stretched the lead further.
Frankie McAvoy kept with the same starting XI that beat Swansea City on Easter Monday, with Browne and Anthony Gordon restored to the squad after missing out through suspension and injury respectively.
The North End skipper therefore was forced to watch on from the bench during the first 45 before being introduced eight minutes into the second half.
Browne said: “I don’t think the scoreline reflects the overall performance.
“We wanted to win and we wanted to go for it right until the end, sometimes you’re going to concede late on and that’s what we did.
“We conceded two late goals which made it look like a generous scoreline for them.
“I thought the boys actually played well in the first half, they scored probably the only two chances that they had in the first half. That’s the difference. They took the two chances they get and we had a few half-chances, there weren’t many clear cut today.
“We need to be clinical, we need to be more defensively solid as well, especially when we’re playing a back five – you should never concede five, even though we changed things later on.
“Even the first two goals were sloppy and looking back at them we’ll want to do better.”
PNE had their moments in the first half and the Bees’ goals arguably came against the run of play as McAvoy’s men continued their positive approach. But as the game wore on Brentford became more ruthless and PNE more open, with three conceded in the final 15 minutes.
Browne said: “It’s probably naive from us to keep going, chasing goals, but that’s what we did. We’d rather try and get goals back than worry about conceding and ultimately that cost us.”