timed tests performance really poor..

Don't worry about time while going through the basics of a topic. Try and understand the concept properly. Try out some practice problems without worrying about time. As bb suggested, once you are comfortable with the topic, try the section tests only in the timed environment. It will help you get comfortable with the ticking clock. (If it were not timed, GMAT would be easy for almost everyone.)
Don't keep looking at the timer while taking the test (it will make you nervous) but you do need to develop an internal clock with practice. (Take some practice tests for that.) Additionally, check out this article. It tells you how to manage your time well.

https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2010/10 ... for-field/