As a part of my Quality Assurance responsibilities at my last position, my instructions were to come up with a test plan and test the product. There was a bit of frustration that I was taking too long to do the testing. As quickly as I could, I tried to put aside my initial emotional reaction that my competence was in question and tried to focus on finding out where the problem was.
I approached the appropriate people about this. I listened to them tell me why they were concerned about my work ("you're taking too long"). I explained my point of view as best I could ("I don't want to deliver shitty software"). We agreed that the problem was a trade-off between the thoroughness of my testing versus a time deadline. I was being very meticulous, very thorough and, unfortunately, we didn't have time. We then had to weigh the importance of quality versus meeting the delivery schedule which is a VERY tough thing to have to decide because both are equally as important.
We agreed that I would cut back on the thoroughness of my test plans, which should make things go much quicker. In return, the team needed to be aware that the product would not be as bullet proof as any of us would like, but that it would be at least at a level that we could accept.