Assuming the Nexus 10 identifies itself uniquely you should be able to check for it with the Device object in the PhoneGap API.
update
To get the performance change on the Nexus device scaling is not going to do it for you since the same number of pixels are still needing to be calculated - however the target-densityDpi
viewport option will hopefully achieve what you require - see this SO Q/A target-densityDpi
On the Nexus 10 the normal resolution is 300 dpi so you would want something like <meta name="viewport" content="width=device-width, target-densityDpi=150">