Compiling zopfli (gcc vc msvc)?

Question

C++ / C#

Compiled the zopfli project with msvc and gcc.
msvc options:

CFLAGS = /W2 /O2 /Ox /Ot /Ob2 /Gw /Gy /GL /arch:SSE2 /fp:fast /MT
CXXFLAGS = $(CFLAGS) /TP /EHsc

gcc options:

CFLAGS = -W -Wall -Wextra -ansi -pedantic -lm -O3 -Wno-unused-function
CXXFLAGS = -W -Wall -Wextra -ansi -pedantic -O3

Performance test:

$ time /c/Users/Lorents/Desktop/zopfli-gcc.exe --i10 /c/Users/Lorents/Desktop/enwik8

real    4m11.807s
user    0m0.000s
sys     0m0.000s

$ time /c/Users/Lorents/Desktop/zopfli-vc.exe --i10 /c/Users/Lorents/Desktop/enwik8

real    4m55.000s
user    0m0.000s
sys     0m0.000s

Can you please tell me how to increase the performance of the MSVC variant?