Comparision of NET2005 to MFC6

machine: eng-azhurav64
MFC6 36.27
NET2005 39.14 and that's with SSE2! WTF?
NET2005 without progress bar: 38.9 so it's not that...

machine: eng-ckorda
MFC6 40.50
NET2005 43.97 with SSE2, FP = fast
NET2005 45.90 with SSE2, FP = precise
NET2005 38.05 SSE disabled, FP = fast
NET2005 36.78 SSE disabled, FP = precise <-- fastest!!!

Looks like SSE2 is SLOWER than the FPU for the rendering loop.
Need to hand-code it and process two pixels at once!

deep zoom benchmark (same coords but 640 x 480, 1x)
machine: eng-ckorda
MFC6 253.27
NET2005 213.03 significantly faster

eng-sfreed: 1024x768, 4096, 4x, GMP = 49 minutes... that's 30 max frames per day

GmpBench

coordinates: deep zoom +132 (768 bits).frs
checksum: 24454011
------------------------
machine: ckci-home (Pentium III)
compiler: VC++ 6.0
GMP version: 4.1.2
GMP target: P6
GmpBench: 446.96
Fractice: 445.71

machine: eng-ckorda (2.66 GHz Intel CoreDuo)
compiler: VC++ 6.0
GMP version: 4.1.2 (my port)
GMP target: Pentium4
GmpBench: 106.02, 105.86

machine: eng-ckorda (2.66 GHz Intel CoreDuo)
compiler: .NET 2005
GMP version: 4.1.2 (my port)
GMP target: Pentium4
GmpBench: 105.25, 105.33

machine: eng-ckorda (2.66 GHz Intel CoreDuo)
compiler: .NET 2005
GMP version: 4.2.2 (Gladman's port)
GMP target: Pentium4
GmpBench: 111.29, 111.34

Many differences between Gladman's 4.2 and my 4.1, likely candidates include
config.h (alloc differences!)
gmp-mparams.h
gmp-impl.h
longlong.h (long long is enabled in Gladman but not mine)

GMP assembler port

benchmark
pc: z / eng-ckorda
file: deep zoom +136 (768 bits).frs
bits: 768

ASM     pass1   pass2
----    -----   -----
generic 173.6   174.3
x86     66.7    65.9
P6      60.0    61.0
P4      59.0    59.0
.NET    71.0    71.0

x86 gives a huge gain, nearly 3x faster!!
p6 is probably worth it, but p4 not
.NET is slower? WTF?

HPAlib test results

default
HPA 6.741
GMP 15.267

deep zoom to +23.frs
HPA 86
GMP 224

Conclusion:
HPA is between 2 and 2.6 times faster than GMP. Unfortunately it runs out of precision at around +32, so it's not much of an improvement over the FPU.