Loading GMail (without the offline module, if it matters) loads 5 separate Iron.exe processes into the task manager, amounting in around 125mb RAM:
I'm not sure whether this is normal behaviour, but it got me a bit worried.
Gmail's login page alone bears 2 processes, and the other 3 load with the inbox.
I checked Google Chrome and it has a similar response, but all 5 processes take up 91mb.