As the rules currently stand a character can make a 5 foot step and then perfom their actions.
Would it be too unbalanced for a character to be able to move 10 feet and then perform their actions at the expense of a feat?
I'd have it have some hefty prerequisites. Otherwise mages and fighters would pick it up and it would be chaos! Chaos I tell you.
Only way I have to do that in my game at present involves losing a leg, so it's a fairly unattractive option.
It's called Pounce ;-)
And there are already several feats doing this in D&D 3.5 (reputedly compatible with Pathfinder RPG).
Plz can i Play a Rogue in your campaig or a Figherter with the 5-step feats for killin spellcasters? I would ruin it in no time!
So my advice: Don't do it.
Think at a halfling cleric who is small and has medium armor. His movement is 15ft. The 5 foot step is now 10. i doubt if this character will walk normal again in combat!
It is not pounce, you can do that only at the end of a charge! And players dont have pounce(maybe the summoner)