Continuous integration and continuous software deployment depend on the mix of automated and manual activities. The automated build and test processes are often intertwined with manual reviews and bug-fixing activities. In this paper, we set off to study how these manual and automated activities influence the speed of reviews and integration. We conduct a case study of two companies developing embedded software, measure the time required for reviewing and integrating software code (alias speed), and conduct a workshop to identify factors which explain the quantitative results. Our results show that the measurement of speed is a good alias for calendar time and triggers improvements better than using measures for velocity. We have also found that the distribution of code repositories, frequent reminders and team proximity decrease the time needed to deploy the software. Our findings are that there is a difference in the structure of code repositories between the fast and slow integration cases, which contributes to the debate on the pros and cons of different repository structures in modern companies.