Powerfunding is a specific costly trick that will quickly grow your town.
When opening the town window there is the number of houses the town currently holds. Powerfunding is based purely on this number. The housenumber determines the growth speed of a town, not the population.
By pressing the fund new buildings button the GR counter gets reset, but town also tries to build one house, this is where you watch the house number of town.
If the house number increases hit the fund new buildings button again. Usually town builds the house within 5 seconds after hitting the button. If these 5 seconds are over and no building is placed you are unlucky, but hit fund new buildings again.
This is used to boost your town from low house count towards high house counts, where town has a much higher growth rate.
Don't try this funding method if towns growth rate is 3 in 1 day or less. If you powerfund at those times you can greatly mess up the house placing and reset the counter numerous times with no gain