It seems to be very specific to Chrome.
My specs are an i7 920 @ 2.67GHz with 6GB of RAM
I tried Chrome without the extensions & the problem persisted.
Disabling the browser script scan had no effect.
I have noticed that the ESET Service is now using 501,000k+ as well. My PC is rarely switched off & has been running for 4 days now. For the first day or so everything was fine & then slowly this problem has appeared, getting worse the longer the PC runs without a reboot.
I am sure the initial memory used by the service was much less than I am seeing now, which makes me suspect there is a memory leak occurring.