To the people having extrusion issues,
1. Pull down your extruders, most of the housings have a certain level of slack in the screw holes, so you can rotate it to adjust the fit, out of the box mine prevented the release bar from properly tensioning on the filament, so I was getting poor layer adhesion and voids, and bumping up the multiplier just made things worse (leave him at 100%),
2. Measure your retraction when cold at the top of the extruder, the filament has a certain amount of stretch, so while holding the release down, note how much you extra you can push / pull at the top of the extruder, for Cartesian with direct extruders this is likely very small, but for deltas, it can be mm,
3. Have a look into your printers extruder settings if they are available, most that I have seen have there jerk rates set way too low, and acceleration too low, meaning there are times your controller is waiting for the extrusion to catch up to your motion rate.
4. for PLA, cooling is key, Even and complete coverage is best, on my delta I printed a duct to lightly blow air over the whole circumference but not directly on the nozzle, it doesn't need much in the way of flow rate, you just want the filament to solidify a few mm from when it exits the nozzle so its ready for the next layer on smaller shapes.