diff --git a/ci-scripts/install-deps.sh b/ci-scripts/install-deps.sh
index 6faf97b..e08c42a 100755
--- a/ci-scripts/install-deps.sh
+++ b/ci-scripts/install-deps.sh
@@ -1,15 +1,16 @@
 #!/usr/bin/env bash
 
-if (( $# != 1 )); then
-  echo "usage: `basename $0` <prefix>" 1>&2
+if (( $# != 2 )); then
+  echo "usage: `basename $0` <prefix> <ntasks>" 1>&2
   exit 1
 fi
 PREFIX=$1
+NTASKS=$2
 
 set -ex
 mkdir -p local/build
 for d in gsl nlopt minuit hdf5; do
   if [ ! -e local/.built.${d} ]; then
-    ./install-${d}.sh ${PREFIX}
+    ./install-${d}.sh ${PREFIX} ${NTASKS}
   fi
 done
diff --git a/ci-scripts/install-gsl.sh b/ci-scripts/install-gsl.sh
index fe39df2..41ed0c2 100755
--- a/ci-scripts/install-gsl.sh
+++ b/ci-scripts/install-gsl.sh
@@ -2,11 +2,12 @@
 
 NAME='gsl-2.6'
 
-if (( $# != 1 )); then
-  echo "usage: `basename $0` <prefix>" 1>&2
+if (( $# != 2 )); then
+  echo "usage: `basename $0` <prefix> <ntasks>" 1>&2
   exit 1
 fi
 PREFIX=$1
+NTASKS=$2
 
 set -ex
 INITDIR=$(pwd -P)
@@ -19,7 +20,7 @@ tar -xzvf ${NAME}.tar.gz
 mkdir -p ${NAME}/build
 cd ${NAME}/build
 ../configure --prefix=${PREFIX}
-make -j4 
+make -j${NTASKS}
 make install
 cd ${INITDIR}/local
 touch .built.gsl
diff --git a/ci-scripts/install-hdf5.sh b/ci-scripts/install-hdf5.sh
index 1788268..c0617e3 100755
--- a/ci-scripts/install-hdf5.sh
+++ b/ci-scripts/install-hdf5.sh
@@ -2,11 +2,12 @@
 
 NAME='hdf5-1.10.5'
 
-if (( $# != 1 )); then
-  echo "usage: `basename $0` <prefix>" 1>&2
+if (( $# != 2 )); then
+  echo "usage: `basename $0` <prefix> <ntasks>" 1>&2
   exit 1
 fi
 PREFIX=$1
+NTASKS=$2
 
 set -ex
 INITDIR=$(pwd -P)
@@ -19,7 +20,7 @@ tar -xzvf ${NAME}.tar.gz
 mkdir ${NAME}/build
 cd ${NAME}/build
 ../configure --prefix=${PREFIX} --enable-cxx
-make -j4 
+make -j${NTASKS}
 make install
 cd ${INITDIR}/local
 touch .built.hdf5
diff --git a/ci-scripts/install-latan.sh b/ci-scripts/install-latan.sh
index 797b07f..3e8a377 100755
--- a/ci-scripts/install-latan.sh
+++ b/ci-scripts/install-latan.sh
@@ -1,10 +1,11 @@
 #!/usr/bin/env bash
 
-if (( $# != 1 )); then
-  echo "usage: `basename $0` <prefix>" 1>&2
+if (( $# != 2 )); then
+  echo "usage: `basename $0` <prefix> <ntasks>" 1>&2
   exit 1
 fi
 PREFIX=$1
+NTASKS=$2
 
 set -ex
 INITDIR=$(pwd -P)
@@ -12,11 +13,11 @@ mkdir -p ${PREFIX}
 cd ${PREFIX}
 PREFIX=$(pwd -P)
 cd ${INITDIR}
-./install-deps.sh ${PREFIX}
+./install-deps.sh ${PREFIX} ${NTASKS}
 cd ..
 ./bootstrap.sh
 mkdir -p build
 cd build
-../configure --prefix=${PREFIX} --with-minuit=${PREFIX} --with-nlopt=${PREFIX} --with-hdf5=${PREFIX} --with-gsl=${PREFIX} CXXFLAGS="${CXXFLAGS} -O3 -march=haswell -mtune=haswell"
-make -j4
+../configure --prefix=${PREFIX} --with-minuit=${PREFIX} --with-nlopt=${PREFIX} --with-hdf5=${PREFIX} --with-gsl=${PREFIX} CXXFLAGS="${CXXFLAGS} -O3 -march=native -mtune=native"
+make -j${NTASKS}
 make install
diff --git a/ci-scripts/install-minuit.sh b/ci-scripts/install-minuit.sh
index 0f6c716..02e96bb 100755
--- a/ci-scripts/install-minuit.sh
+++ b/ci-scripts/install-minuit.sh
@@ -1,11 +1,12 @@
 #!/usr/bin/env bash
 
 
-if (( $# != 1 )); then
-  echo "usage: `basename $0` <prefix>" 1>&2
+if (( $# != 2 )); then
+  echo "usage: `basename $0` <prefix> <ntasks>" 1>&2
   exit 1
 fi
 PREFIX=$1
+NTASKS=$2
 
 set -ex
 INITDIR=$(pwd -P)
@@ -18,7 +19,7 @@ git clone https://github.com/root-project/root.git
 cd root/math/minuit2/
 mkdir build; cd build
 cmake .. -Dminuit2_standalone=ON -DCMAKE_INSTALL_PREFIX=${PREFIX}
-make -j4 
+make -j${NTASKS}
 make install
 cd ${INITDIR}/local
 touch .built.minuit
diff --git a/ci-scripts/install-nlopt.sh b/ci-scripts/install-nlopt.sh
index 3851888..23b1572 100755
--- a/ci-scripts/install-nlopt.sh
+++ b/ci-scripts/install-nlopt.sh
@@ -2,11 +2,12 @@
 
 NAME='2.6.1'
 
-if (( $# != 1 )); then
-  echo "usage: `basename $0` <prefix>" 1>&2
+if (( $# != 2 )); then
+  echo "usage: `basename $0` <prefix> <ntasks>" 1>&2
   exit 1
 fi
 PREFIX=$1
+NTASKS=$2
 
 set -ex
 INITDIR=$(pwd -P)
@@ -20,7 +21,7 @@ NAME=nlopt-${NAME}
 mkdir -p ${NAME}/build
 cd ${NAME}/build
 cmake -DCMAKE_INSTALL_PREFIX=${PREFIX} -DCMAKE_BUILD_WITH_INSTALL_NAME_DIR=TRUE -DCMAKE_INSTALL_NAME_DIR="${PREFIX}/lib" ..
-make -j4 
+make -j${NTASKS}
 make install
 cd ${INITDIR}/local
 touch .built.nlopt