diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index d09b640fe..a61f0dd75 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -17,27 +17,6 @@ jobs:
     - name: build
       run: cmake --build build --target ci_test_clang_cxx20
 
-  ci_clang_analyze:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: install_ninja
-        run: |
-          sudo apt update
-          sudo apt install ninja-build
-        shell: bash
-      - name: install_clang
-        run: |
-          wget https://apt.llvm.org/llvm.sh
-          chmod +x llvm.sh
-          sudo ./llvm.sh 11
-          sudo apt-get install clang-tools-11
-        shell: bash
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_clang_analyze
-
   ci_test_clang:
     runs-on: ubuntu-latest
     steps:
@@ -69,94 +48,31 @@ jobs:
       - name: build
         run: cmake --build build --target ci_test_gcc
 
-  ci_test_valgrind:
+  ci_static_analysis:
     runs-on: ubuntu-latest
     container: nlohmann/json-ci:latest
+    strategy:
+      matrix:
+        target: [ci_clang_tidy, ci_cppcheck, ci_test_valgrind, ci_test_clang_sanitizer, ci_test_amalgamation, ci_clang_analyze, ci_cpplint]
     steps:
       - uses: actions/checkout@v2
       - name: cmake
         run: cmake -S . -B build -DJSON_CI=On
       - name: build
-        run: cmake --build build --target ci_test_valgrind
+        run: cmake --build build --target ${{ matrix.target }}
 
-  ci_cppcheck:
+  ci_cmake_options:
     runs-on: ubuntu-latest
     container: nlohmann/json-ci:latest
+    strategy:
+      matrix:
+        target: [ci_test_diagnostics, ci_test_noexceptions, ci_test_noimplicitconversions]
     steps:
       - uses: actions/checkout@v2
       - name: cmake
         run: cmake -S . -B build -DJSON_CI=On
       - name: build
-        run: cmake --build build --target ci_cppcheck
-
-  ci_cpplint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_cpplint
-
-  ci_clang_tidy:
-    runs-on: ubuntu-latest
-    container: nlohmann/json-ci:latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_clang_tidy
-
-  ci_test_amalgamation:
-    runs-on: ubuntu-latest
-    container: nlohmann/json-ci:latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_test_amalgamation
-
-  ci_test_diagnostics:
-    runs-on: ubuntu-latest
-    container: nlohmann/json-ci:latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_test_diagnostics
-
-  ci_test_noexceptions:
-    runs-on: ubuntu-latest
-    container: nlohmann/json-ci:latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_test_noexceptions
-
-  ci_test_noimplicitconversions:
-    runs-on: ubuntu-latest
-    container: nlohmann/json-ci:latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_test_noimplicitconversions
-
-  ci_test_clang_sanitizer:
-    runs-on: ubuntu-latest
-    container: nlohmann/json-ci:latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: cmake
-        run: cmake -S . -B build -DJSON_CI=On
-      - name: build
-        run: cmake --build build --target ci_test_clang_sanitizer
+        run: cmake --build build --target ${{ matrix.target }}
 
   ci_test_coverage:
     runs-on: ubuntu-latest
@@ -177,3 +93,16 @@ jobs:
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           path-to-lcov: /__w/json/json/build/json.info.filtered.noexcept
+
+  ci_test_compilers:
+    runs-on: ubuntu-latest
+    container: nlohmann/json-ci:latest
+    strategy:
+      matrix:
+        compiler: [g++-4.8, g++-4.9, g++-5, g++-7, g++-8, g++-9, g++-10, clang++-3.5, clang++-3.6, clang++-3.7, clang++-3.8, clang++-3.9, clang++-4.0, clang++-5.0, clang++-6.0, clang++-7, clang++-8, clang++-9, clang++-10, clang++-11]
+    steps:
+      - uses: actions/checkout@v2
+      - name: cmake
+        run: cmake -S . -B build -DJSON_CI=On
+      - name: build
+        run: cmake --build build --target ci_test_compiler_${{ matrix.compiler }}
diff --git a/.travis.yml b/.travis.yml
index c5208b31f..bdfbe722b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -54,30 +54,6 @@ matrix:
 
   # Linux / GCC
 
-  - os: linux
-    compiler: gcc
-    env: COMPILER=g++-4.8
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-4.8', 'ninja-build']
-
-  - os: linux
-    compiler: gcc
-    env: COMPILER=g++-4.9
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-4.9', 'ninja-build']
-
-  - os: linux
-    compiler: gcc
-    env: COMPILER=g++-5
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-5', 'ninja-build']
-
   - os: linux
     compiler: gcc
     env: COMPILER=g++-6
@@ -86,124 +62,6 @@ matrix:
         sources: ['ubuntu-toolchain-r-test']
         packages: ['g++-6', 'ninja-build']
 
-  - os: linux
-    compiler: gcc
-    env: COMPILER=g++-7
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-7', 'ninja-build']
-
-  - os: linux
-    compiler: gcc
-    env: COMPILER=g++-8
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-8', 'ninja-build']
-
-  - os: linux
-    compiler: gcc
-    env: COMPILER=g++-9
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-9', 'ninja-build']
-
-  - os: linux
-    compiler: gcc
-    env:
-      - COMPILER=g++-9
-      - CXX_STANDARD=17
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-9', 'ninja-build']
-
-  # Linux / Clang
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-3.5
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.5']
-        packages: ['g++-6', 'clang-3.5', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-3.6
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.6']
-        packages: ['g++-6', 'clang-3.6', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-3.7
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.7']
-        packages: ['g++-6', 'clang-3.7', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-3.8
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-6', 'clang-3.8', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-3.9
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-6', 'clang-3.9', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-4.0
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-4.0']
-        packages: ['g++-6', 'clang-4.0', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-5.0
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-5.0']
-        packages: ['g++-6', 'clang-5.0', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-6.0
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-6.0']
-        packages: ['g++-6', 'clang-6.0', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env: COMPILER=clang++-7
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-7']
-        packages: ['g++-6', 'clang-7', 'ninja-build']
-
-  - os: linux
-    compiler: clang
-    env:
-      - COMPILER=clang++-7
-      - CXX_STANDARD=17
-    addons:
-      apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-7']
-        packages: ['g++-7', 'clang-7', 'ninja-build']
-
 ################
 # build script #
 ################
diff --git a/cmake/ci.cmake b/cmake/ci.cmake
index 4e0d74b12..b167cc93b 100644
--- a/cmake/ci.cmake
+++ b/cmake/ci.cmake
@@ -30,7 +30,7 @@ execute_process(COMMAND ${CPPCHECK_TOOL} --version OUTPUT_VARIABLE CPPCHECK_TOOL
 string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" CPPCHECK_TOOL_VERSION "${CPPCHECK_TOOL_VERSION}")
 message(STATUS "🔖 Cppcheck ${CPPCHECK_TOOL_VERSION} (${CPPCHECK_TOOL})")
 
-find_program(GCC_TOOL NAMES g++-HEAD g++-11 g++-10 g++)
+find_program(GCC_TOOL NAMES g++-HEAD g++-11 g++-latest)
 execute_process(COMMAND ${GCC_TOOL} --version OUTPUT_VARIABLE GCC_TOOL_VERSION ERROR_VARIABLE GCC_TOOL_VERSION)
 string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" GCC_TOOL_VERSION "${GCC_TOOL_VERSION}")
 message(STATUS "🔖 GCC ${GCC_TOOL_VERSION} (${GCC_TOOL})")
@@ -85,7 +85,7 @@ find_program(SCAN_BUILD_TOOL NAMES scan-build-11 scan-build)
 file(GLOB_RECURSE SRC_FILES ${PROJECT_SOURCE_DIR}/include/nlohmann/*.hpp)
 
 ###############################################################################
-# Different C++ Standards.
+# Thorough check with recent compilers
 ###############################################################################
 
 set(CLANG_CXXFLAGS "-std=c++11                        \
@@ -784,6 +784,26 @@ add_custom_target(ci_cmake_flags
     COMMENT "Check CMake flags"
 )
 
+###############################################################################
+# Use more installed compilers.
+###############################################################################
+
+foreach(COMPILER g++-4.8 g++-4.9 g++-5 g++-7 g++-8 g++-9 g++-10 clang++-3.5 clang++-3.6 clang++-3.7 clang++-3.8 clang++-3.9 clang++-4.0 clang++-5.0 clang++-6.0 clang++-7 clang++-8 clang++-9 clang++-10 clang++-11)
+    find_program(COMPILER_TOOL NAMES ${COMPILER})
+    if (COMPILER_TOOL)
+        add_custom_target(ci_test_compiler_${COMPILER}
+            COMMAND CXX=${COMPILER} ${CMAKE_COMMAND}
+                -DCMAKE_BUILD_TYPE=Debug -GNinja
+                -DJSON_BuildTests=ON -DJSON_FastTests=ON
+                -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_compiler_${COMPILER}
+            COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER}
+            COMMAND cd ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER} && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" --output-on-failure
+            COMMENT "Compile and test with ${COMPILER}"
+        )
+    endif()
+    unset(COMPILER_TOOL CACHE)
+endforeach()
+
 ###############################################################################
 # Clean up all generated files.
 ###############################################################################
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 15f55dfa5..d8c586425 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -2,6 +2,7 @@ option(JSON_Sanitizer "Build test suite with Clang sanitizer" OFF)
 option(JSON_Valgrind "Execute test suite with Valgrind" OFF)
 option(JSON_NoExceptions "Build test suite without exceptions" OFF)
 option(JSON_Coverage "Build test suite with coverage information" OFF)
+option(JSON_FastTests "Whether to skip expensive tests" OFF)
 
 # download test data
 include(${CMAKE_CURRENT_SOURCE_DIR}/../cmake/download_test_data.cmake)
@@ -112,10 +113,17 @@ foreach(file ${files})
         target_link_libraries(${testcase} PRIVATE --coverage)
     endif()
 
-    add_test(NAME "${testcase}"
-        COMMAND ${testcase} ${DOCTEST_TEST_FILTER} --no-skip
-        WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
-    )
+    if (JSON_FastTests)
+        add_test(NAME "${testcase}"
+            COMMAND ${testcase} ${DOCTEST_TEST_FILTER}
+            WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+        )
+    else()
+        add_test(NAME "${testcase}"
+            COMMAND ${testcase} ${DOCTEST_TEST_FILTER} --no-skip
+            WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+        )
+    endif()
     set_tests_properties("${testcase}" PROPERTIES LABELS "all" FIXTURES_REQUIRED TEST_DATA)
 
     if(JSON_Valgrind)