The strong impact of the coronavirus (COVID-19) on the construction industry has been studied by many researchers, but few have identified the individual factors that affected the efficiency of construction projects and analyzed them based on the size of the organization administering the project. This study aims to do just that: identify the factors that altered the efficiency of construction projects during COVID-19 and analyze how they impacted small, medium, and large construction companies. To accomplish this goal, a comprehensive literature search was performed and was followed by a questionnaire survey. Sixty-three responses to the survey were statistically analyzed to determine the critical challenges to project efficiency faced during the pandemic and revealed that the most common were shortages of materials and workers, including material transportation/delivery problems and mental stress originating from an imbalance of work and life; reduced efficiency and increased absenteeism of employees due to illness were also significant. Interestingly, it was found that an organization's size played an important role in how it was affected. The results of this study will assist researchers and professionals in understanding the difficulties that various sizes of construction companies face during a pandemic and will help them develop preventive measures for future events.