cpbWhat is your ram speed?
I'm getting 1m44s in Linux, with an older 16-core 1950x, no OC.
Texture VOP is using UV coordinate as face S/T when UV attribute exists, even for PTex. You can delete the UV attribute to get around the issue, or (if you need to keep the UV attribute for other uses), you can wire shading global's S/T into Texture VOP's UV input (using Float to Vector VOP, set S as first component and set T as second component).
Due to the requirement that all ptex faces must be quads (http://www.sidefx.com/docs/houdini/shade/ptex.html), mantra will split non-quads into quads when baking into ptex, ending up with different number of faces than the original mesh. Unfortunately GetPTextureID VOP simply returns primitive index if the object is not subd. So when you use ptex texture on an object that has triangles, primitive index won't match up with what's inside ptex and the renders will appear incorrect.
A workaround is to enable subd on the object being rendered (using “Mantra catmull-clark” style).