With a SonarQube Enterprise Edition, you can increase the number of Compute Engine workers to speed up the processing of analysis reports. Projects analyses in queue can then be handled simultaneously by SonarQube.
Still, SonarQube prevents reports corresponding to a same project to be computed in parallel. The consequence is that, when several branches / Pull Requests of a same project are simultaneously analyzed, reports can take long to be processed.
The user experience is not good, specifically when working with short-lived branches / Pull Requests that could be quickly computed and for which developers would expect a quick feedback loop.
SonarQube should be able to compute simultaneously reports that relate to a same project.