This one will be quick and easy. Recently I found out about wonderful feature of Marlin 3D printer firmware called firmware retraction. So what is the difference between firmware retraction and normal retraction made by Slic3r? It is easy, you can set different speeds for retract and recover.
Basically you can pull out the plastic really fast and save time but you can’t try to force the filament back in as fast as it would cause many problems.
When the recover speed is too big, you risk filament drive stripping piece of the filament and cause jam. Also there is a slight lag between the filament actually flowing out of the extruder nozzle, especially with bowden extruder setup. Newest Slic3r (tested with 1.2.6) has support for firmware retraction so you can easily try it out.
And it has one more GIANT advantage. You can tweak your retract during the print with simple G-code commands. That means no need to reslice the model just to tweak it! I love this!