DominoPDF does not need any specific server settings to operate, however as with any process which utilises the Domino HTTP task it’s good practice to examine your settings for optimum usage.
In the Domino Directory (names.nsf) there are settings for controlling agent and web agent usage which can have an effect on DominoPDF.
Domino Directory >> Server >> Internet Protocols >> Domino Web Engine >> Web Agents >> Run web agents concurrently?
Domino Directory >> Server >> Server Tasks >> Agent Manager >> Max concurrent agents
These settings can be adjusted accordingly to reflect the usage in your specific environment.