Advanced reading comprehension on the Gmat Verbal is the core skill required for a good verbal score. More than just how fast you read, how well you understand what you have just read is more important. For example, did you need to go back and re-read the first sentence? That would be called “regression”, and is one of a few bad reading habits you should aim to reduce. This requires diligent and conscious practice. Another bad reading habit is internal vocalization – Saying the words out loud in your head. It is impossible to completely eliminate internal vocalization, but a little less of it will add very valuable seconds on your exam.
It is common, especially for non-avid readers (notice I did not say non-native english speakers), to run out of time towards the end of the Verbal section. Keep in mind that the Verbal section is less adaptive than the Quant section. Particularly important for people aiming for a high verbal score, one or two mistakes will drop your raw score by 3 to 5 points. If you were doing well in the beginning by taking your time, the extra minutes you took will catch up on you towards the end.
It pays off to improve your reading speed and your reading comprehension. As with other valuable skills, you cannot improve overnight. Instead, you have to be conscious about your shortcomings in reading comprehension and begin improving that skill early on in your preparation. The few seconds you waste or save through bad or good reading habits on each question, will add up against or in your favor towards the end of the test.
Some helpful links to improve your reading comprehension on the Gmat
Try this free speed reading test to determine your reading speed. Make sure to read at your normal pace.
In addition, this short course to improve you reading skills is a great place to start.