In my experience, if a child is slow (i.e. counts on their fingers, thinks deeply about a problem or tries to overanalyze a problem) they can take longer than their peers - and then, they cannot finish a test - my child writes slowly, so he could not finish one math problem and hence his scores dropped by 5% in an achievement test. He was frustrated when the scores came out because he knew that the drop in scores in math were because he could not finish the test. We don't worry because my child has known issues with writing and he is getting help for it.
I second blackcat's suggestion of using a computerized program like ixl, xtramath or bigbrainz and drill her on her math facts first. If after that, she still seems slow and hates math, definitely have her tested.
