"New Slack" follows lead single and title track "Popfly", which was came together in a jam session on a drive. The track sees Nau seeking out answers, accompanied by drums and woodwind instruments.

Discussing the single, Nau explains: “The earliest memory I have of this song is playing it in the tailgate of Benny’s Volvo-Benny on bass, & Oliver playing sax. Benny would send me that phone memo a lot over the next couple years. It only made sense to record it for this album."