Pinpoint the areas you are spending too much time on. Are you reading the passages themselves for longer than you should be? Are you constantly re-reading questions? Are you exploring myriad different explanations (i.e. second guessing yourself) when trying to solve a particular problem? It depends on what's going on when you're doing the passages, but let's discuss this a bit further in case one of these happens to be the issue.
Reading the passage itself
- This should, ideally, take no more than 3-4 minutes. How? Well, basically don't see the forest for the trees - i.e. don't try to memorize or expertly understand every single piece of information given to you during the time that you read the actual passage. Let the highlighting tool do the work for you - if you see something that you feel might be of importance later (concluding sentences, ratios, constants, etc.), highlight it and move on, don't try to memorize it. Spend time understanding what topic is being presented and spend the time during the first read-through to get a decent understanding of tables and graphs (the best time to understand these is the first time around when they can be put into context).
Re-reading questions
- Sometimes a by-product of a lack of focus. Try to keep in the back of your mind that each question has an answer that is rooted in basic principals. If the question just seems
too challenging then it was probably made so on purpose. Try to break it down and undress the language to reveal a more simplistic question.
Exploring too many explanations/concepts when presented w/ question
- This can be a marker of a lack of experience in taking passages (as
@sillyjoe mentioned - timing can work out later down the road after taking a lot of practice passages) or can be an indication that you need to do higher intensity post-game analysis. When you analyze the questions you got right
and wrong after taking a passage, analyze the entire problem (question + all answer choices) and make sure you completely understand the question and not just the explanations when reviewing. This will help make a subconscious connection between of the type of questions (and the language used) and the to-be-expected explanation. This can make you prepared to quickly answer the next similar question you see.
Hope this helps some!!
basically double the time. 
