Multiple WordPress installation Question

Hello,
I wanted to know if there is any potential issue (cpu or memory overhead constraint or possible system conflict) with running the Postman plugin in multiple WordPress installations that run on the same physical server.

I plan on having quite a few wordpress installations running (potential to reach over 100 separate installations) from my personal server and wanted to make sure this was a safe route. They would all be setup for different email account (i.e the clients).