Strikes me that the person not doing good work here is your boss and, probably, your manager.
What did the meeting you have actually accomplish? How will it help you or the rest of the team improve?
If the project or the timeline are so important, how does any of this help you get there? If I have a real deadline that I need somebody to hit, I'm going to explain the context of the deadline to them—how else are they going to make good decisions to actually hit the deadline?—and I'm going to continue talking with them throughout the whole process so that both of us understand how the project is progressing compared to expectations. If something is slowing the work down, what should we do about that? If there really is some mismatch in skills, what can we do to help you improve, and how should we adjust the rest of our plans?
Feedback like this should never come as a surprise. I don't like absolute rules in any complex scenario, but this is about as close to an absolute rule for leading a team as I can imagine. Even if the overall assessment of your work is "fair"—how likely is that?—the fact that it came out of nowhere for you and that you are not sure what will happen next is straight-up bad leadership.
It sounds like you're feeling guilty about the feedback, or that it means you are not an effective programmer. The one upside about this situation is that there are specific reasons to believe it really is them, not you. The downside is that there probably isn't much you can realistically do to change the situation—after all, if your leaders aren't effective, how much do you expect working "harder" to change anything? The main thing that I've found helpful in these situations is to remember that your "performance" is very context-specific, and the context here sucks. I've often found it hard to feel this viscerally, but even just thinking this rationally and recognizing my feelings for what they are has helped.
Recognizing this also helped me get in the right state of mind to decide what to do next. I've had situations like this a couple of times; the first time I ended up switching companies and the second time I switched teams within the same company—both times, it made a larger difference than I expected.
What did the meeting you have actually accomplish? How will it help you or the rest of the team improve?
If the project or the timeline are so important, how does any of this help you get there? If I have a real deadline that I need somebody to hit, I'm going to explain the context of the deadline to them—how else are they going to make good decisions to actually hit the deadline?—and I'm going to continue talking with them throughout the whole process so that both of us understand how the project is progressing compared to expectations. If something is slowing the work down, what should we do about that? If there really is some mismatch in skills, what can we do to help you improve, and how should we adjust the rest of our plans?
Feedback like this should never come as a surprise. I don't like absolute rules in any complex scenario, but this is about as close to an absolute rule for leading a team as I can imagine. Even if the overall assessment of your work is "fair"—how likely is that?—the fact that it came out of nowhere for you and that you are not sure what will happen next is straight-up bad leadership.
It sounds like you're feeling guilty about the feedback, or that it means you are not an effective programmer. The one upside about this situation is that there are specific reasons to believe it really is them, not you. The downside is that there probably isn't much you can realistically do to change the situation—after all, if your leaders aren't effective, how much do you expect working "harder" to change anything? The main thing that I've found helpful in these situations is to remember that your "performance" is very context-specific, and the context here sucks. I've often found it hard to feel this viscerally, but even just thinking this rationally and recognizing my feelings for what they are has helped.
Recognizing this also helped me get in the right state of mind to decide what to do next. I've had situations like this a couple of times; the first time I ended up switching companies and the second time I switched teams within the same company—both times, it made a larger difference than I expected.