Chrome was one of the Apps that updated when I started the Portable apps platform. I'm running from an 8gig USB 2.0 drive under Windows 8.1 will all current updates. Of the 8GB, well over 7GB are free. When I start Chrome, it lags so far behind any input that it's impossible to use. The internet is slow, but even something as simple as typing a URL takes at least 60 sec before any characters appear. Forget using a scroll bar it is many seconds before the full page is cached and the scroll is responsive. Once it does, the responsiveness is normal, but OMG, I'm an old timer and I don't recall anything this bad.
Newer versions of Chrome are quite large (over 150MB) and will write to the flash drive constantly. So, they'll be slower than browsers like Firefox which are much more efficient.
Sometimes, the impossible can become possible, if you're awesome!
The performance of Chrome depends a lot on the performance of the usb drive itself. I've tested Chrome with a cheap Emtec 16Gb drive and it goes as slow as yours. The same portable app folder has been copied to a fast Hitachi drive and it runs as fast as a bullet.
Cautionary tale: avoid cheap USB drives with slow I/O throughput if you plan to use Portable Apps often.
Regards,