> Does this mean that the Mysterious Shared Memory Slowdown problem has been
> fixed in -current?
> 

This has been solved to a large extent, though there still are unhandled cases.

> If so, is there any chance of a back-port Official Patch for 1.0?  I've got a

The required changes should be easy to back-port to 1.0 source. The changes
are in vm_object.c (one added routine), pmap.c (one added routine),
vm_mmap.c (changed vm_mmap() logic when mapping a file) and pmap.h
(one #define).

-pk