diff --git a/.github/workflows/ci-julia-nightly.yml b/.github/workflows/ci-julia-nightly.yml
index 94e3854a..d018ed30 100644
--- a/.github/workflows/ci-julia-nightly.yml
+++ b/.github/workflows/ci-julia-nightly.yml
@@ -4,6 +4,14 @@ on:
     branches: [master, main]
     tags: ["*"]
   pull_request:
+
+concurrency:
+  # group by workflow and ref; the last slightly strange component ensures that for pull
+  # requests, we limit to 1 concurrent job, but for the master branch we don't
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ (github.ref != 'refs/heads/master' && github.ref != 'refs/heads/main') || github.run_number }}
+  # Cancel intermediate builds, but only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+
 env:
   PYTHON: ~
 jobs:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6bbbb6f2..cf751e1c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,6 +4,14 @@ on:
     branches: [master, main]
     tags: ["*"]
   pull_request:
+
+concurrency:
+  # group by workflow and ref; the last slightly strange component ensures that for pull
+  # requests, we limit to 1 concurrent job, but for the master branch we don't
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ (github.ref != 'refs/heads/master' && github.ref != 'refs/heads/main') || github.run_number }}
+  # Cancel intermediate builds, but only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+
 env:
   PYTHON: ~
 jobs:
@@ -19,7 +27,8 @@ jobs:
         os:
           - ubuntu-latest
         threads:
-          - '2'
+          - '1'
+          - '5'
         arch:
           - x64
         include:
@@ -34,7 +43,7 @@ jobs:
           - arch: x64
             os: windows-latest
             version: '1'
-            threads: '1'  
+            threads: '1'
     steps:
       - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v1
@@ -56,16 +65,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Install binary dependencies
-        run: sudo apt-get update && sudo apt-get install -y xorg-dev mesa-utils xvfb libgl1 freeglut3-dev libxrandr-dev libxinerama-dev libxcursor-dev libxi-dev libxext-dev
       - uses: julia-actions/setup-julia@v1
         with:
           version: '1'
       - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-docdeploy@v1
-        with:
-          prefix: xvfb-run
         env:
           GKSwstype: nul # Fix for Plots with GR backend.
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}