How much ever fast I try to read and comprehend the RC passage ,I am able to attend as much as 9-11 questions only and that too not with 100% accuracy .I don't generally attend the verbal ability part except for summaries sometimes ,if I have some 2-3 minutes left .So I finally end up getting marks below 25 .How to improve ?

I would suggest you to not leave VA entirely. I find VA to be the safest area to score as there is no negative marking in TITA questions. My advice would be to start with Summary or Odd one Out, then do RCs, and with the time left, do Parajumbles. Even if you are not 100% sure of the answers in parajumbles and odd one out, write what you feel, as you have nothing to lose there.

Verbal is the deal-breaker. If verbal turns out to be easy, then you can invest just 10 mins and get all right! That is equivalent to getting two RCs right with 90% accuracy in half the time.
But if RCs have more than 4 questions and the VA is moderately tough, then the priority should be RCs.The tables have turned in this case.
If the section turns out to be tough( long Rc with complex language or tough VA), then prioritize high accuracy with low attempts.

thanks abhishek