diff --git a/.github/workflows/nestbuildmatrix.yml b/.github/workflows/nestbuildmatrix.yml
index b2860ab553..97f0e9ea41 100644
--- a/.github/workflows/nestbuildmatrix.yml
+++ b/.github/workflows/nestbuildmatrix.yml
@@ -522,8 +522,9 @@ jobs:
         cpp_compiler: ["gcc"]
 
         # available use flags (all default to "OFF"):
-        # openmp, mpi, python, gsl, ltdl, boost, sionlib, libneurosim, optimize, warning, userdoc, music
+        # openmp, mpi, python, gsl, ltdl, boost, sionlib, libneurosim, optimize, warning, userdoc, music, readline
         use:
+          - "optimize, warning"
           - "boost, optimize, warning"
           - "openmp, python, gsl, ltdl, boost, optimize, warning"
           - "mpi, python, gsl, ltdl, boost, optimize, warning"
@@ -562,26 +563,47 @@ jobs:
 
       - name: "Install Linux system dependencies"
         run: |
-          sudo apt-get update
           # https://github.com/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-README.md
-          sudo apt-get install ccache
-          sudo apt-get install libltdl-dev libreadline6-dev libncurses5-dev libgsl0-dev python3-all-dev jq libpcre3 libpcre3-dev
-          sudo apt-get install tcl8.6 tcl8.6-dev tk8.6-dev
-          # Install MPI dependencies regardless of whether we compile NEST with or without MPI, so the installation of MPI4Py works
-          sudo apt-get install openmpi-bin libopenmpi-dev
-          sudo apt-get install libboost-filesystem-dev libboost-regex-dev libboost-wave-dev libboost-python-dev libboost-program-options-dev libboost-test-dev
-          sudo apt-get install pkg-config
+          sudo apt-get update
+          sudo apt-get install \
+                           ccache \
+                           python3-all-dev \
+                           jq \
+                           libpcre3 libpcre3-dev \
+                           pkg-config
+          # not sure why these would be required:
+          #   sudo apt-get install tcl8.6 tcl8.6-dev tk8.6-dev
           sudo ldconfig
 
+      - name: "Install Readline dependencies"
+        if: "${{ contains(matrix.use, 'readline') }}"
+        run: "sudo apt-get install libreadline6-dev libncurses5-dev"
+
+      - name: "Install LTDL dependencies"
+        if: "${{ contains(matrix.use, 'ltdl') }}"
+        run: "sudo apt-get install libltdl-dev"
+
+      - name: "Uninstall Boost development libraries"
+        if: "${{ ! contains(matrix.use, 'boost') }}"
+        run: |
+          apt list --installed 'libboost*'
+          sudo apt-get remove --autoremove 'libboost*-dev'
+
+      - name: "Install Boost dependencies"
+        if: "${{ contains(matrix.use, 'boost') }}"
+        run: "sudo apt-get install libboost-filesystem-dev libboost-regex-dev libboost-wave-dev libboost-python-dev libboost-program-options-dev libboost-test-dev"
+
+      - name: "Install OpenMPI development dependencies"
+        if: "${{ contains(matrix.use, 'mpi') }}"
+        run: "sudo apt-get install openmpi-bin libopenmpi-dev"
+
       - name: "Install GSL system dependencies"
         if: "${{ contains(matrix.use, 'gsl') }}"
-        run: |
-          sudo apt-get install libgsl0-dev
+        run: "sudo apt-get install libgsl0-dev"
 
       - name: "Install HDF5 system dependencies"
         if: "${{ contains(matrix.use, 'hdf5') }}"
-        run: |
-          sudo apt-get install libhdf5-dev
+        run: "sudo apt-get install libhdf5-dev"
 
       - name: "Restore ccache"
         # Using CCache to re-use compiled objects from prior runs that have the same
@@ -617,13 +639,24 @@ jobs:
       - name: "Install Python dependencies"
         run: |
           python -m pip install --upgrade pip setuptools
+          python -m pip install --force-reinstall --upgrade cython  # this finds a broken preinstall if not explicitly forced
           python -c "import setuptools; print('package location:', setuptools.__file__)"
-          python -m pip install --force-reinstall --upgrade scipy 'junitparser>=2' numpy pytest pytest-timeout pytest-xdist cython matplotlib terminaltables pandoc pandas
-          # Install mpi4py regardless of whether we compile NEST with or without MPI, so regressiontests/issue-1703.py will run in both cases
-          python -m pip install --force-reinstall --upgrade mpi4py
+          pip list
+
+      - name: "Install Python test dependencies" 
+        # These could go to a separate venv…
+        run: |
+          python -m pip install 'junitparser>=2' pytest pytest-timeout pytest-xdist terminaltables 
+          python -m pip install numpy scipy pandas matplotlib
           test \! -e "=2"   # assert junitparser is correctly quoted and '>' is not interpreted as shell redirect
           python -c "import pytest; print('package location:', pytest.__file__)"
-          pip list
+
+      - name: "Install Python doc dependencies"
+        run: "python -m pip install pandoc"
+        
+      - name: "Install Python mpi dependencies" 
+        if: "${{ contains(matrix.use, 'mpi') }}"
+        run: "python -m pip install --force-reinstall --upgrade mpi4py"
 
       - name: "Install h5py"
         if: "${{ contains(matrix.use, 'hdf5') }}"
@@ -649,6 +682,13 @@ jobs:
           PYLIB_DIR="$(python3 -c "import sysconfig; print(sysconfig.get_path('include'))" | sed 's/include/lib/')"
           ./build_support/install_csa-libneurosim.sh $PYLIB_DIR
 
+      - name: "List available packages"
+        run: |
+          gcc --version
+          python --version
+          apt list
+          pip list
+
       - name: "Configure NEST build"
         env:
           CMAKE_C_COMPILER_LAUNCHER: ccache