Theres going to be a balance between speed and accuracy. Many questions you can get by with just reading the first and last lines and getting enough of an idea in order to answer. However, that includes a high risk of being duped into a wrong answer or missing a vital clue.
IMO the least risky way to speed things up is knowing all the lab values by heart. The less you have to open the lab values tab, the quicker you can get through some of the insanely long lab values some question stems give you.
Another strategy I use at times is to leave any question with lab values to the end, that way you can get the short questions done quickly and have more time for the lengthy ones. Also some folks have said that there are around 1-2 questions of statistics per block, so being able to answer those questions in a few seconds can add valuable time.