diff --git a/client/sources-linux/Makefile b/client/sources-linux/Makefile
index 6e62f9ec..b8377ade 100644
--- a/client/sources-linux/Makefile
+++ b/client/sources-linux/Makefile
@@ -71,7 +71,7 @@ resources_library_compressed_string_txt.c: ../gen_resource_header.py resources/l
 		resources/library_compressed_string.txt $(XZARGS)
 
 resources/bootloader.pyc: ../gen_python_bootloader.py ../../pupy/packages/all/pupyimporter.py ../../pupy/pp.py
-	$(PYTHON) $(PFLAGS) ../gen_python_bootloader.py $(DEBUG_ADD)
+	$(PYTHON) -OO $(PFLAGS) ../gen_python_bootloader.py $(DEBUG_ADD)
 
 resources_bootloader_pyc.c: ../gen_resource_header.py resources/bootloader.pyc
 	$(PYTHON) $(PFLAGS) $+ $(XZARGS)
@@ -101,7 +101,7 @@ resources/libssl.so: $(LIBSSL)
 	rm -f $@.tmp
 
 resources/library.zip: ../build_library_zip.py ../additional_imports.py
-	$(PYTHON) $(PFLAGS) $<
+	$(PYTHON) -OO $(PFLAGS) $<
 
 resources_python27_so.c: ../gen_resource_header.py resources/python27.so
 	$(PYTHON) $(PFLAGS) $+ $(XZARGS)
diff --git a/client/sources-linux/buildenv.sh b/client/sources-linux/buildenv.sh
index 4373f195..c1e3ecbb 100755
--- a/client/sources-linux/buildenv.sh
+++ b/client/sources-linux/buildenv.sh
@@ -275,13 +275,13 @@ cd /usr/src/automake-1.15
 ./configure --prefix=/usr; make; make install
 
 CFLAGS="-O2 -pipe -DCLOCK_MONOTONIC=1 -UHAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC -U_FILE_OFFSET_BITS" \
- python -O -m pip install pyuv --no-binary :all:
+ python -OO -m pip install pyuv --no-binary :all:
 
-python -O -m pip uninstall -y cffi
+python -OO -m pip uninstall -y cffi
 
 cd /usr/lib/python2.7
-python -O -m compileall -q
 python -m compileall -q
+python -OO -m compileall -q
 
 find -name "*.so" | while read f; do strip \$f; done
 
@@ -501,13 +501,13 @@ tar zxf automake-1.15.tar.gz
 cd /usr/src/automake-1.15
 ./configure --prefix=/usr; make; make install
 
-python -O -m pip install pyuv --no-binary :all:
+python -OO -m pip install pyuv --no-binary :all:
 
-python -O -m pip uninstall -y cffi
+python -OO -m pip uninstall -y cffi
 
 cd /usr/lib/python2.7
-python -O -m compileall -q
 python -m compileall -q
+python -OO -m compileall -q
 
 find -name "*.so" | while read f; do strip \$f; done
 
@@ -535,7 +535,7 @@ TEMPLATES=`readlink -f ../../pupy/payload_templates`
 
 cd buildenv/lin64/usr/lib/python2.7
 zip -y \
-    -x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyo" \
+    -x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyc" \
     -x "*test/*" -x "*tests/*" -x "*examples/*" \
     -x "*.egg-info/*" -x "*.dist-info/*" \
     -x "idlelib/*" -x "lib-tk/*" -x "tk*"  -x "tcl*" \
@@ -544,7 +544,7 @@ cd -
 
 cd buildenv/lin32/usr/lib/python2.7
 zip -y \
-    -x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyo" \
+    -x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyc" \
     -x "*test/*" -x "*tests/*" -x "*examples/*" \
     -x "*.egg-info/*" -x "*.dist-info/*" \
     -x "idlelib/*" -x "lib-tk/*" -x "tk*"  -x "tcl*" -x "*.la" \
diff --git a/client/sources/Makefile b/client/sources/Makefile
index 17d04513..84e1bea2 100644
--- a/client/sources/Makefile
+++ b/client/sources/Makefile
@@ -9,7 +9,7 @@ $(error You must specify an architecture - win64 or win32)
 endif
 
 CC := $(BUILDENV)/$(ARCH)/cl.sh
-PYTHON := $(BUILDENV)/$(ARCH)/python.sh -O
+PYTHON := $(BUILDENV)/$(ARCH)/python.sh
 HOST_PYTHON := python
 
 ifeq "$(ARCH)" "win64"
diff --git a/client/sources/buildenv.sh b/client/sources/buildenv.sh
index d57834da..581ec875 100755
--- a/client/sources/buildenv.sh
+++ b/client/sources/buildenv.sh
@@ -152,13 +152,13 @@ sed -i $WINEPREFIX/system.reg -e 's@"ProductName"="Microsoft Windows XP"@"Produc
 unset WINEPREFIX
 
 for prefix in $WINE32 $WINE64; do
-    WINEPREFIX=$prefix wine C:\\Python27\\python -O -m pip install --upgrade pip
-    WINEPREFIX=$prefix wine C:\\Python27\\python -O -m pip install --upgrade setuptools
-    WINEPREFIX=$prefix wine C:\\Python27\\python -O -m pip install --upgrade $PACKAGES
-    WINEPREFIX=$prefix wine C:\\Python27\\python -O -m pip install --upgrade --no-binary :all: psutil
-    WINEPREFIX=$prefix wine C:\\Python27\\python -O -m pip uninstall -y cffi
-    WINEPREFIX=$prefix wine C:\\Python27\\python -O -m compileall -q C:\\Python27\\Lib || true
+    WINEPREFIX=$prefix wine C:\\Python27\\python -OO -m pip install --upgrade pip
+    WINEPREFIX=$prefix wine C:\\Python27\\python -OO -m pip install --upgrade setuptools
+    WINEPREFIX=$prefix wine C:\\Python27\\python -OO -m pip install --upgrade $PACKAGES
+    WINEPREFIX=$prefix wine C:\\Python27\\python -OO -m pip install --upgrade --no-binary :all: psutil
+    WINEPREFIX=$prefix wine C:\\Python27\\python -OO -m pip uninstall -y cffi
     WINEPREFIX=$prefix wine C:\\Python27\\python -m compileall -q C:\\Python27\\Lib || true
+    WINEPREFIX=$prefix wine C:\\Python27\\python -OO -m compileall -q C:\\Python27\\Lib || true
 done
 
 # WINEPREFIX=$WINE32 wine C:\\Python27\\python.exe -m easy_install -Z $PYWIN32
@@ -168,7 +168,7 @@ cat >$WINE32/python.sh <<EOF
 #!/bin/sh
 unset WINEARCH
 export WINEPREFIX=$WINE32
-exec wine C:\\\\Python27\\\\python.exe "\$@"
+exec wine C:\\\\Python27\\\\python.exe -OO "\$@"
 EOF
 chmod +x $WINE32/python.sh
 
@@ -189,7 +189,7 @@ cat >$WINE64/python.sh <<EOF
 #!/bin/sh
 unset WINEARCH
 export WINEPREFIX=$WINE64
-exec wine C:\\\\Python27\\\\python.exe "\$@"
+exec wine C:\\\\Python27\\\\python.exe -OO "\$@"
 EOF
 chmod +x $WINE64/python.sh
 
@@ -237,7 +237,7 @@ rm -f ${TEMPLATES}/windows-x86.zip
 for dir in Lib DLLs; do
     cd $dir
     zip -q -y \
-	-x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyo" -x "*.chm" \
+	-x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyc" -x "*.chm" \
 	-x "*test/*" -x "*tests/*" -x "*examples/*" -x "pythonwin/*" \
 	-x "idlelib/*" -x "lib-tk/*" -x "tk*"  -x "tcl*" \
 	-x "*.egg-info/*" -x "*.dist-info/*" -x "*.exe" \
@@ -251,7 +251,7 @@ rm -f ${TEMPLATES}/windows-amd64.zip
 for dir in Lib DLLs; do
     cd $dir
     zip -q -y \
-	-x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyo" -x "*.chm" \
+	-x "*.a" -x "*.o" -x "*.whl" -x "*.txt" -x "*.py" -x "*.pyc" -x "*.chm" \
 	-x "*test/*" -x "*tests/*" -x "*examples/*"  -x "pythonwin/*" \
 	-x "idlelib/*" -x "lib-tk/*" -x "tk*"  -x "tcl*" \
 	-x "*.egg-info/*" -x "*.dist-info/*" -x "*.exe" \