I am a PhD student works in computational theory. I have been doing coursework for nearly three years and right now I am starting to reading research papers. I am making progress very slowly, taking about two to three months to read a paper: even after reading it, I have questions. I have to actually verify every and each sentence of the paper which requires mathematical knowledge, and I have done enough mathematics coursework. I am getting feedback that I am reading too slowly. I have tried to work hard as much as possible, but it is not giving much results. Although there were many times in the past in which I am able to complete the incomplete proofs given in research paper. Struggle basically means completing the incomplete claims or theorems of the research paper.
Question : Is it okay to struggle with the content of research paper you are reading? and Is it going to improve with time? How to be efficient in this situation?
What seems to me little troubling here is I am in a surveying phase (reading research papers), then I will move to publication phase. So first I have read the paper then only I can work on them. I don't How much time other PhD students take to read a research paper. If I am taking 2-3 months for just one paper, is it okay?