Hi andreea, you are definitely right. I also realized that I should not be too concerned with my supervisor's comments;I just think that maybe my supervisor also had a bad day.

Hi all,
I'm a 4th year PhD student in pure math at an university in the US (the length of out program takes normally 5-6 years; and we don't require holding a master degree to get in PhD). I'm currently working on is a brand new field and has variety of applications in both physics and engineering. But because it's new, there are few materials that you can read and learn (basically, no text books, only research papers), and it took me 1.5 years on pure reading and learning since my 3rd year(We learn master courses in the 1st and 2nd year, and move onto research topic in the 3rd year). My supervisor was not helpful during my learning period, he rarely taught me, and even I tried to ask him, he only gives very brief explanations. I think it's because he wrote most of the papers that I was reading and he believed those techniques should be mastered quickly. So I just have mastered the techniques from previous works and started to produce new stuff at the beginning of the second semester of my 4th year.
However, about 2 months ago, my supervisor told me that my progress was slow and I should have produced new things. I felt very anxious when I heard of it and started work 10hrs/day for 1 month, and luckily I was able to produce something new last week. However, I kept getting stuck after this,and now I'm feeling a bit frustrated. So I would like to ask if most of PhDs have spent a period of frustration during their training? Or a sense of slowness?