Why does one slice cause more print time?

I downloaded a file that was already in gcode and it called for 5 hours and 47 minutes to print. Since it was already in gcode I went and found the file's STL file and made my own gcode with Slic3r. When I loaded this file into Pronterface it said it would now take 6 hours and 50 minutes to print.,

What would cause this? Have I been doing something wrong all this time and making my prints take longer than needed?

When a file is sliced, it will take the user chosen parameters to create the G-code. Therefore, if you change some of the parameters e.g. alter the infill ratio or whatever, you will get a different sized file. Having said that, I have sliced an STL with identical settings and got 2 slightly different sized files!

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Waitaki 3D Printer

I opened the gcode in notepad and here are the first 15 or so lines from each, I don't see what would cause the extra print time??? I see the parameter speed is double and the first layer is 0.30mm more. Would either of those cause this?

Original file, faster print time:
; layer_height = 0.4
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.4
; perimeter_speed = 60
; infill_speed = 60
; travel_speed = 130
; nozzle_diameter = 0.5
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.53mm
; infill extrusion width = 0.53mm
; solid infill extrusion width = 0.53mm
; top infill extrusion width = 0.53mm
; first layer extrusion width = 0.40mm

The file I made into gcode and and hour longer print time:

; layer_height = 0.4
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.4
; perimeter_speed = 30
; infill_speed = 60
; travel_speed = 130
; nozzle_diameter = 0.5
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.53mm
; infill extrusion width = 0.53mm
; solid infill extrusion width = 0.53mm
; top infill extrusion width = 0.53mm
; first layer extrusion width = 0.70mm

Err.. your perimeter speed in the second one is 1/2 of what it is in the first one.

Since the perimeter is the outside of the object (apart from the bottom that is on the build plate), your print will take longer depending on how much surface area (excluding the bottom) the object has.

I wasn't sure if parameter speed was just outside edges and wasn't sure how much that would change things, but obviously its the main factor. Thanks!