Trouble isolating x64 slowdown

[David Morgan <dmorgan at aechelon dot com>]

Hello devs,

	In my pursuit of debugging the WoW64 performance issues we have 
seen with Cygwin ever since 1.5.20, I have been attempting perform 
change-by-change builds of winsup from July 2006, so that I can isolate
the specific change(s) responsible through process of elimination.  Using
the Time Machine, a colleague found two points during that month where
performance degraded on x64 systems.

	I am having no end of difficulty building a working DLL, however.
I have gotten closest by using Cygwin 1.5.24 as my build platform (1.5.12
and 1.7.1 went badly), but, when I try to run any of the built EXEs (ps,
kill, etc), I get the following error:

The application failed to initialize properly (0xc0000005)

When I perform an objdump -x on my DLL, here's all I get for the import
table:

There is an import table in .idata at 0x61160000

The Import Tables (interpreted .idata section contents)
 vma:            Hint    Time      Forward  DLL       First
                 Table   Stamp     Chain    Name      Thunk
 00160000       65536e65 6870616d 4165726f 00000000 754f0240

In contrast, the stock DLL includes all sorts of dependencies.

Can anyone recommend best practices for building such an old cygwin DLL?
I've read and re-read the current instructions in the FAQ.

Best Regards,

David