Not sure of the version, assuming latest. It's usually not after visiting one site, it's usually over a period of time, I can just have 1 tab on and still 9gb upwards regardless of what is open. To the last quesiton, it's subjective because it can be after a period of using Chrome, but not immedietaly on opening.
You can have the latest DEV (developer) version or the latest STABLE version.
The DEV version could have flaws not worth chasing down (unless you are into that sort of thing). With the DEV version, it is easier to get infected since extensions can be installed from untrusted sources. At the moment, the STABLE versions are starting with the number 44. The DEV versions are starting with the number 46.
I would keep Chrome installed to see if I could stumble across the reason for the high resource usage - however, you might actually have a life