Camera Raw + Photoshop Elements

A while back there was an issue with the cropping being slow with the photoshop elements acr version and from that we (fellow photoshop elements users) were able to determine is that the photoshop elements version of acr indeed does not use the GPU like photoshop's acr does. So that would be a major reason your seeing the difference in speed between the pse acr and photoshop acr.

Also of note is that the photoshop acr version has a gpu on/off preference, so the gpu preference in the pse preferences does not affect the camera raw plugin.

If your interested in reading about how camera raw uses the gpu:

https://helpx.adobe.com/camera-raw/kb/acr-gpu-faq.html

It's simply not the same just as Elements is not the same as Photoshop in feature parity.