Hi Karthik,
I understand it may be hard to perform better when you don't have time to review the marked questions. I had a similar problem at the beginning: too many questions marked and no time to review them. When you mark a question, do you pick an answer, or do you leave it unanswered? I'd recommend not to leave any question unanswered, as unanswered questions would be counted as wrong anyway.
During my preparation, the possibility of reviewing questions helped me a lot, as sometimes I overlooked a "NOT" or which process group the question was focusing on and noticed it upon reviewing the question later on.
Did you find some questions harder than others to answer? E.g., situational questions vs. formula-based questions?
One thing that helped me, particularly with questions having a long scenario description, was to read the beginning to set the context and the question at the very end, to better direct my attention while reading the whole description. This approach may help you focus and hopefully take less time to understand what the question is about.
I'd also recommend this tutorial which guides you through the types of questions in the exam, providing tips and recommendations for each of them:
https://www.project-management-prepcast.com/pmp-exam-questions
One last thing: did you take the exam simulations always around the same time during the day? I used to take the exam sim in the afternoon; one day, I had a meeting at that time, so I decided to anticipate the exam simulation late in the morning. It was mind-blowing: my performance improved simply because I took the exam simulation earlier. I was much faster, while often in the afternoon, I could feel I was tired around 3 hours into the exam and found it very hard to get to the end of it. And I'm not saying you have to take the exam in the morning: this is entirely personal. I would just recommend - if you have the chance - to try to take some at different times and see when you feel better.
Gabriella