This will prevent textures from being released if one of its surfaces is still
in use by the stateblock. We have similar constructions in d3d8 and d3d9, but
those won't prevent the wined3d texture from being released.

Also include idle time in kernel time.

If you really have e.g. multiple draws to the same drawable, this is not
enough, and you should use the StrictDrawOrdering registry setting. In the
other cases it just slows things down unnecessarily.