Chrome is capable of offloading certain graphical operations to the GPU via WebGL, as well as decoding video. But again, whether this is what’s causing the increase in load depends on usage patterns. It may be something else.
VirtualGL has just received an EGL front-end, which allows it to be used with recent versions of Chrome and Firefox for GPU offload.
As far as GPU selection is concerned, this is really outside the scope of ThinLinc. Some investigation would be required to determine which is best suited for your particular use case.