This is a common problem...ideally 2-3 min should be spent reading the RC to get familiar to the argument structure and then 1-2 min/per question.
Another strategy that works for some people is to read the RC carefully and understand it fully...and then answer the questions like a breeze.
These are just some of the strategies that I try to follow...Actually it depends from person to person what suits him...the key is to practice as much as possible and make ur own strategy.
But the main aim is to finish each RC within 7-8 min.
These are just my opinions...hope they help