diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 258309b519..464d1fde4d 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -180,76 +180,13 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'skip:ci') }}
     env:
       RUST_BACKTRACE: full
-      # PLATFORM_INDEPENDENT_TESTS are tests that do not depend on the underlying OS.
-      # They are currently only run on Linux to speed up the CI.
-      PLATFORM_INDEPENDENT_TESTS: >-
-        test__colorize
-        test_array
-        test_asyncgen
-        test_binop
-        test_bisect
-        test_bool
-        test_bytes
-        test_call
-        test_cmath
-        test_collections
-        test_complex
-        test_contains
-        test_copy
-        test_dataclasses
-        test_decimal
-        test_decorators
-        test_defaultdict
-        test_deque
-        test_dict
-        test_dictcomps
-        test_dictviews
-        test_dis
-        test_enumerate
-        test_exception_variations
-        test_float
-        test_fractions
-        test_genericalias
-        test_genericclass
-        test_grammar
-        test_range
-        test_index
-        test_int
-        test_int_literal
-        test_isinstance
-        test_iter
-        test_iterlen
-        test_itertools
-        test_json
-        test_keyword
-        test_keywordonlyarg
-        test_list
-        test_long
-        test_longexp
-        test_operator
-        test_ordered_dict
-        test_pep646_syntax
-        test_pow
-        test_raise
-        test_richcmp
-        test_scope
-        test_set
-        test_slice
-        test_sort
-        test_string
-        test_string_literals
-        test_strtod
-        test_structseq
-        test_subclassinit
-        test_super
-        test_syntax
-        test_tstring
-        test_tuple
-        test_unary
-        test_unpack
-        test_unpack_ex
-        test_weakref
-        test_yield_from
+      # Tests that can be flaky when running with multiple processes `-j 2`. We will use `-j 1` for these.
+      FLAKY_MP_TESTS: >-
+        test_class
+        test_eintr
+        test_multiprocessing_fork
+        test_multiprocessing_forkserver
+        test_multiprocessing_spawn
     name: Run snippets and cpython tests
     runs-on: ${{ matrix.os }}
     strategy:
@@ -304,17 +241,23 @@ jobs:
         run: python -m pip install -r requirements.txt && pytest -v
         working-directory: ./extra_tests
 
-      - name: run cpython platform-independent tests
-        if: runner.os == 'Linux'
+      - name: Detect available cores
+        id: cores
+        shell: bash
         run: |
-          target/release/rustpython -m test -j 1 -u all --slowest --fail-env-changed --timeout 600 -v ${{ env.PLATFORM_INDEPENDENT_TESTS }}
-        timeout-minutes: 45
+          cores=$(python -c 'print(__import__("os").process_cpu_count())')
+          echo "cores=${cores}" >> $GITHUB_OUTPUT
+
+      - name: Run CPython tests
+        run: |
+          target/release/rustpython -m test -j ${{ steps.cores.outputs.cores }} ${{ join(matrix.extra_test_args, ' ') }} --slowest --fail-env-changed --timeout 600 -v -x ${{ env.FLAKY_MP_TESTS }} ${{ join(matrix.skips, ' ') }}
+        timeout-minutes: ${{ matrix.timeout }}
         env:
           RUSTPYTHON_SKIP_ENV_POLLUTERS: true
 
-      - name: run cpython platform-dependent tests
+      - name: Run flaky MP CPython tests
         run: |
-          target/release/rustpython -m test -j 1 ${{ join(matrix.extra_test_args, ' ') }} --slowest --fail-env-changed --timeout 600 -v -x ${{ env.PLATFORM_INDEPENDENT_TESTS }} ${{ join(matrix.skips, ' ') }}
+          target/release/rustpython -m test -j 1 ${{ join(matrix.extra_test_args, ' ') }} --slowest --fail-env-changed --timeout 600 -v ${{ env.FLAKY_MP_TESTS }}
         timeout-minutes: ${{ matrix.timeout }}
         env:
           RUSTPYTHON_SKIP_ENV_POLLUTERS: true