diff --git a/misc/factor.sh b/misc/factor.sh
index 9db0a29fcb..eb231cd565 100755
--- a/misc/factor.sh
+++ b/misc/factor.sh
@@ -12,41 +12,41 @@ ARCH=
 WORD=
 
 ensure_program_installed() {
-    echo -n "Checking for $1..."
-    result=`type -p $1`
-    if ! [[ -n $result ]] ; then
-        echo "not found!"
-        echo "Install $1 and try again."
-        exit 1
-    fi
-    echo "found!"
+	echo -n "Checking for $1..."
+	result=`type -p $1`
+	if ! [[ -n $result ]] ; then
+		echo "not found!"
+		echo "Install $1 and try again."
+		exit 1
+	fi
+	echo "found!"
 }
 
 check_ret() {
-    RET=$?
-    if [[ $RET -ne 0 ]] ; then
-       echo $1 failed
-       exit 2
-    fi
+	RET=$?
+	if [[ $RET -ne 0 ]] ; then
+	   echo $1 failed
+	   exit 2
+	fi
 }
 
 check_gcc_version() {
-    GCC_VERSION=`gcc --version`
-    if [[ $GCC_VERSION == *3.3.* ]] ; then
-        echo "You have a known buggy version of gcc (3.3)"
-        echo "Install gcc 3.4 or higher and try again."
-        exit 3
-    fi
+	GCC_VERSION=`gcc --version`
+	if [[ $GCC_VERSION == *3.3.* ]] ; then
+		echo "You have a known buggy version of gcc (3.3)"
+		echo "Install gcc 3.4 or higher and try again."
+		exit 3
+	fi
 }
 
 check_installed_programs() {
-    ensure_program_installed chmod
-    ensure_program_installed uname
-    ensure_program_installed git
-    ensure_program_installed wget
-    ensure_program_installed gcc
-    ensure_program_installed make
-    check_gcc_version
+	ensure_program_installed chmod
+	ensure_program_installed uname
+	ensure_program_installed git
+	ensure_program_installed wget
+	ensure_program_installed gcc
+	ensure_program_installed make
+	check_gcc_version
 }
 
 check_factor_exists() {
@@ -58,152 +58,158 @@ check_factor_exists() {
 }
 
 find_os() {
-    uname_s=`uname -s`
-    case $uname_s in
-        CYGWIN_NT-5.2-WOW64) OS=windows-nt;;
-        *CYGWIN_NT*) OS=windows-nt;;
-        *CYGWIN*) OS=windows-nt;;
-        *darwin*) OS=macosx;;
-        *Darwin*) OS=macosx;;
-        *linux*) OS=linux;;
-        *Linux*) OS=linux;;
-    esac
+	uname_s=`uname -s`
+	case $uname_s in
+		CYGWIN_NT-5.2-WOW64) OS=windows-nt;;
+		*CYGWIN_NT*) OS=windows-nt;;
+		*CYGWIN*) OS=windows-nt;;
+		*darwin*) OS=macosx;;
+		*Darwin*) OS=macosx;;
+		*linux*) OS=linux;;
+		*Linux*) OS=linux;;
+	esac
 }
 
 find_architecture() {
-    uname_m=`uname -m`
-    case $uname_m in
-       i386) ARCH=x86;;
-       i686) ARCH=x86;;
-       *86) ARCH=x86;;
-       "Power Macintosh") ARCH=ppc;;
-    esac
+	uname_m=`uname -m`
+	case $uname_m in
+	   i386) ARCH=x86;;
+	   i686) ARCH=x86;;
+	   *86) ARCH=x86;;
+	   "Power Macintosh") ARCH=ppc;;
+	esac
 }
 
 write_test_program() {
-    echo "#include <stdio.h>" > $C_WORD.c
-    echo "int main(){printf(\"%d\", 8*sizeof(void*)); return 0; }" >> $C_WORD.c
+	echo "#include <stdio.h>" > $C_WORD.c
+	echo "int main(){printf(\"%d\", 8*sizeof(void*)); return 0; }" >> $C_WORD.c
 }
 
 find_word_size() {
-    C_WORD=factor-word-size
-    write_test_program
-    gcc -o $C_WORD $C_WORD.c
-    WORD=$(./$C_WORD)
-    check_ret $C_WORD
-    rm -f $C_WORD*
+	C_WORD=factor-word-size
+	write_test_program
+	gcc -o $C_WORD $C_WORD.c
+	WORD=$(./$C_WORD)
+	check_ret $C_WORD
+	rm -f $C_WORD*
 }
 
 set_factor_binary() {
-    case $OS in
-        windows-nt) FACTOR_BINARY=factor-nt;;
-        macosx) FACTOR_BINARY=./Factor.app/Contents/MacOS/factor;;
-        *) FACTOR_BINARY=factor;;
-    esac
+	case $OS in
+		windows-nt) FACTOR_BINARY=factor-nt;;
+		macosx) FACTOR_BINARY=./Factor.app/Contents/MacOS/factor;;
+		*) FACTOR_BINARY=factor;;
+	esac
 }
 
 echo_build_info() {
-    echo OS=$OS
-    echo ARCH=$ARCH
-    echo WORD=$WORD
-    echo FACTOR_BINARY=$FACTOR_BINARY
-    echo MAKE_TARGET=$MAKE_TARGET
-    echo BOOT_IMAGE=$BOOT_IMAGE
+	echo OS=$OS
+	echo ARCH=$ARCH
+	echo WORD=$WORD
+	echo FACTOR_BINARY=$FACTOR_BINARY
+	echo MAKE_TARGET=$MAKE_TARGET
+	echo BOOT_IMAGE=$BOOT_IMAGE
 }
 
 set_build_info() {
-    if ! [[ -n $OS && -n $ARCH && -n $WORD ]] ; then
-        echo "OS, ARCH, or WORD is empty.  Please report this"
-        exit 5
-    fi
-    MAKE_TARGET=$OS-$ARCH-$WORD
-    BOOT_IMAGE=boot.$ARCH.$WORD.image
+	if ! [[ -n $OS && -n $ARCH && -n $WORD ]] ; then
+		echo "OS, ARCH, or WORD is empty.  Please report this"
+		exit 5
+	fi
+	MAKE_TARGET=$OS-$ARCH-$WORD
+	BOOT_IMAGE=boot.$ARCH.$WORD.image
 }
 
 find_build_info() {
-    find_os
-    find_architecture
-    find_word_size
-    set_factor_binary
-    set_build_info
-    echo_build_info
+	find_os
+	find_architecture
+	find_word_size
+	set_factor_binary
+	set_build_info
+	echo_build_info
 }
 
 git_clone() {
-    echo "Downloading the git repository from factorcode.org..."
-    git clone git://factorcode.org/git/factor.git
-    check_ret git
+	echo "Downloading the git repository from factorcode.org..."
+	git clone git://factorcode.org/git/factor.git
+	check_ret git
 }
 
 git_pull_factorcode() {
-    git pull git://factorcode.org/git/factor.git
-    check_ret git
+	git pull git://factorcode.org/git/factor.git
+	check_ret git
 }
 
 cd_factor() {
-    cd factor
-    check_ret cd
+	cd factor
+	check_ret cd
+}
+
+make_clean() {
+	make clean
+	check_ret make
 }
 
 make_factor() {
-    make $MAKE_TARGET
-    check_ret make
+	make $MAKE_TARGET -j5
+	check_ret make
 }
 
 delete_boot_images() {
-    echo "Deleting old images..."
-    rm $BOOT_IMAGE > /dev/null 2>&1
-    rm $BOOT_IMAGE.* > /dev/null 2>&1
+	echo "Deleting old images..."
+	rm $BOOT_IMAGE > /dev/null 2>&1
+	rm $BOOT_IMAGE.* > /dev/null 2>&1
 }
 
 get_boot_image() {
-    wget http://factorcode.org/images/latest/$BOOT_IMAGE
-    check_ret wget
+	wget http://factorcode.org/images/latest/$BOOT_IMAGE
+	check_ret wget
 }
 
 maybe_download_dlls() {
-    if [[ $OS == windows-nt ]] ; then
-        wget http://factorcode.org/dlls/freetype6.dll
-        check_ret
-        wget http://factorcode.org/dlls/zlib1.dll
-        check_ret
-        chmod 777 *.dll
-        check_ret
-    fi
+	if [[ $OS == windows-nt ]] ; then
+		wget http://factorcode.org/dlls/freetype6.dll
+		check_ret
+		wget http://factorcode.org/dlls/zlib1.dll
+		check_ret
+		chmod 777 *.dll
+		check_ret
+	fi
 }
 
 bootstrap() {
-    ./$FACTOR_BINARY -i=$BOOT_IMAGE
+	./$FACTOR_BINARY -i=$BOOT_IMAGE
 }
 
 usage() {
-    echo "usage: $0 install|update"
+	echo "usage: $0 install|update"
 }
 
 case "$1" in
-    install)
+	install)
 		check_factor_exists
-        check_installed_programs
-        find_build_info
-        git_clone
-        cd_factor
-        make_factor
-        get_boot_image
-        maybe_download_dlls
-        bootstrap
-    ;;
+		check_installed_programs
+		find_build_info
+		git_clone
+		cd_factor
+		make_factor
+		get_boot_image
+		maybe_download_dlls
+		bootstrap
+	;;
 
-    update)
-        check_installed_programs
-        find_build_info
-        git_pull_factorcode
-        make_factor
-        delete_boot_images
-        get_boot_image
-        bootstrap
-    ;;
+	update)
+		check_installed_programs
+		find_build_info
+		git_pull_factorcode
+		make_clean
+		make_factor
+		delete_boot_images
+		get_boot_image
+		bootstrap
+	;;
 
-    *)
-        usage
-    ;;
+	*)
+		usage
+	;;
 esac