(This is sort of related to JENKINS-2947, but doesn't really belong there.)
The Perforce configuration for a job doesn't provide much flexibility if you want to run a job on various slaves.
The path to the executable means that the job becomes fixed to an OS (more or less), and doesn't allow for slaves configured with Perforce in a different location.
The P4PORT setting is also a problem (for me). We have slaves that run in various locations, each of which may have their own local p4 proxy which would be optimal. As it stands now, we have to choose one server that is the best compromise for all locations.