diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 78ba210f92..e718e1fc11 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -131,6 +131,9 @@ jobs:
           python=${{ matrix.python-version }}
           ${{ env.CONDA_CHANNEL_LABEL }}${{ env.CONDA_VERSION }}
 
+      - name: Install development conda
+        run: pip install git+https://github.com/zklaus/conda@lazy-index && python -m conda init --install
+
       # TODO: how can we remove this step?
       - name: Install Self
         run: pip install -e .
@@ -214,6 +217,9 @@ jobs:
       - name: Install CodSpeed
         run: pip install git+https://github.com/kenodegard/pytest-codspeed.git@fix-outerr-redirects#egg=pytest-codspeed
 
+      - name: Install development conda
+        run: pip install git+https://github.com/zklaus/conda@lazy-index && python -m conda init --install
+
       # TODO: how can we remove this step?
       - name: Install Self
         run: pip install -e .
@@ -234,6 +240,77 @@ jobs:
           token: ${{ secrets.CODSPEED_TOKEN }}
           run: $CONDA/envs/test/bin/pytest --codspeed
 
+  # linux memray
+  linux-memray:
+    # only run test suite if there are code changes
+    needs: changes
+    if: needs.changes.outputs.code == 'true'
+
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        # https://github.com/conda-incubator/setup-miniconda#use-a-default-shell
+        shell: bash -el {0}  # bash exit immediately on error + login shell
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ['3.12']
+
+    steps:
+      - name: Checkout Source
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+        with:
+          fetch-depth: 0
+
+      - name: Hash + Timestamp
+        run: echo "HASH=${{ runner.os }}-${{ runner.arch }}-Py${{ matrix.python-version }}-memray-$(date -u "+%Y%m")" >> $GITHUB_ENV
+
+      - name: Cache Conda
+        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9
+        with:
+          path: ~/conda_pkgs_dir
+          key: cache-${{ env.HASH }}
+
+      - name: Setup Miniconda
+        uses: conda-incubator/setup-miniconda@a4260408e20b96e80095f42ff7f1a15b27dd94ca
+        with:
+          condarc-file: .github/condarc
+          run-post: false  # skip post cleanup
+
+      - name: Conda Install
+        run: >
+          conda install
+          --yes
+          --file tests/requirements.txt
+          --file tests/requirements-${{ runner.os }}.txt
+          --file tests/requirements-ci.txt
+          python=${{ matrix.python-version }}
+          ${{ env.CONDA_CHANNEL_LABEL }}${{ env.CONDA_VERSION }}
+          pytest-memray
+
+      - name: Install CodSpeed
+        run: pip install git+https://github.com/kenodegard/pytest-codspeed.git@fix-outerr-redirects#egg=pytest-codspeed
+
+      - name: Install development conda
+        run: pip install git+https://github.com/zklaus/conda@lazy-index && python -m conda init --install
+
+      # TODO: how can we remove this step?
+      - name: Install Self
+        run: pip install -e .
+
+      - name: Conda Info
+        # view test env info (not base)
+        run: python -m conda info --verbose
+
+      - name: Conda Config
+        run: conda config --show-sources
+
+      - name: Conda List
+        run: conda list --show-channel-urls
+
+      - name: Run memray
+        run: python -m pytest -k memray --memray
+
   # windows test suite
   windows:
     # only run test suite if there are code changes
@@ -295,6 +372,9 @@ jobs:
           python=${{ matrix.python-version }}
           ${{ env.CONDA_CHANNEL_LABEL }}::conda
 
+      - name: Install development conda
+        run: pip install git+https://github.com/zklaus/conda@lazy-index && python -m conda init --install
+
       # TODO: how can we remove this step?
       - name: Install Self
         run: pip install -e .
@@ -414,6 +494,9 @@ jobs:
           python=${{ matrix.python-version }}
           ${{ env.CONDA_CHANNEL_LABEL }}::conda
 
+      - name: Install development conda
+        run: pip install git+https://github.com/zklaus/conda@lazy-index && python -m conda init --install
+
       # TODO: how can we remove this step?
       - name: Install Self
         run: pip install -e .
diff --git a/conda_build/index.py b/conda_build/index.py
index bcb9c6a9d0..04e20b47e4 100644
--- a/conda_build/index.py
+++ b/conda_build/index.py
@@ -6,7 +6,7 @@
 from os.path import dirname
 
 from conda.base.context import context
-from conda.core.index import get_index
+from conda.core.index import Index
 from conda.exceptions import CondaHTTPError
 from conda.utils import url_path
 from conda_index.index import update_index as _update_index
@@ -102,26 +102,24 @@ def get_build_index(
             if subdir == "noarch":
                 subdir = context.subdir
             try:
-                # get_index() is like conda reading the index, not conda_index
+                # Index() is like conda reading the index, not conda_index
                 # creating a new index.
-                cached_index = get_index(
-                    channel_urls=urls,
+                cached_index = Index(
+                    channels=urls,
                     prepend=not omit_defaults,
-                    use_local=False,
-                    use_cache=context.offline,
                     platform=subdir,
+                    use_local=False,
                 )
             # HACK: defaults does not have the many subfolders we support.  Omit it and
             #          try again.
             except CondaHTTPError:
                 if "defaults" in urls:
                     urls.remove("defaults")
-                cached_index = get_index(
-                    channel_urls=urls,
-                    prepend=omit_defaults,
-                    use_local=False,
-                    use_cache=context.offline,
+                cached_index = Index(
+                    channels=urls,
+                    prepend=not omit_defaults,
                     platform=subdir,
+                    use_local=False,
                 )
 
         local_index_timestamp = os.path.getmtime(index_file)
diff --git a/conda_build/inspect_pkg.py b/conda_build/inspect_pkg.py
index 54ec2c6f28..2f2ec97e0a 100644
--- a/conda_build/inspect_pkg.py
+++ b/conda_build/inspect_pkg.py
@@ -16,7 +16,7 @@
 from conda.api import Solver
 from conda.base.context import context
 from conda.cli.common import specs_from_args
-from conda.core.index import get_index
+from conda.core.index import Index
 from conda.core.prefix_data import PrefixData
 from conda.models.records import PrefixRecord
 
@@ -173,7 +173,7 @@ def test_installable(channel: str = "defaults") -> bool:
     success = True
     for subdir in ["osx-64", "linux-32", "linux-64", "win-32", "win-64"]:
         log.info("######## Testing subdir %s ########", subdir)
-        for prec in get_index(channel_urls=[channel], prepend=False, platform=subdir):
+        for prec in Index(channels=[channel], prepend=False, platform=subdir):
             name = prec["name"]
             if name in {"conda", "conda-build"}:
                 # conda can only be installed in the root environment
diff --git a/conda_build/skeletons/cpan.py b/conda_build/skeletons/cpan.py
index 31213054d1..0ac5395f65 100644
--- a/conda_build/skeletons/cpan.py
+++ b/conda_build/skeletons/cpan.py
@@ -21,7 +21,7 @@
 from os.path import basename, dirname, exists, join
 
 import requests
-from conda.core.index import get_index
+from conda.core.index import Index
 from conda.exceptions import CondaError, CondaHTTPError
 from conda.gateways.connection.download import TmpDownload, download
 from conda.gateways.disk.create import TemporaryDirectory
@@ -695,7 +695,7 @@ def latest_pkg_version(pkg):
     """
     :returns: the latest version of the specified conda package available
     """
-    r = Resolve(get_index())
+    r = Resolve(Index())
     try:
         pkg_list = sorted(r.get_pkgs(MatchSpec(pkg)))
     except:
diff --git a/pyproject.toml b/pyproject.toml
index 12fe4731f6..da1ef47e8f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -124,12 +124,15 @@ filterwarnings = [
   # elevate conda-build's deprecated warning to an error
   "error::PendingDeprecationWarning:conda_build",
   "error::DeprecationWarning:conda_build",
+  "ignore:Python 3.14 will, by default, filter extracted tar archives:DeprecationWarning:conda_package_streaming",
   # ignore numpy.distutils error
   'ignore:\s+`numpy.distutils` is deprecated:DeprecationWarning:conda_build._load_setup_py_data',
   # ignore conda-index error
   "ignore::PendingDeprecationWarning:conda_index",
   "ignore::DeprecationWarning:conda_index",
   "ignore:Python 3.14 will, by default, filter extracted tar archives and reject files or modify their metadata:DeprecationWarning",
+  "ignore:conda.core.index._supplement_index_with_system is pending deprecation:PendingDeprecationWarning:conda",
+  "ignore:conda.core.index._make_virtual_package is pending deprecation:PendingDeprecationWarning:conda",
 ]
 markers = [
   "serial: execute test serially (to avoid race conditions)",
@@ -137,6 +140,7 @@ markers = [
   "sanity: execute the sanity tests",
   "no_default_testing_config: used internally to disable monkeypatching for testing_config",
   "benchmark: execute the benchmark tests",
+  "memray: memory use tests",
 ]
 minversion = 3.0
 norecursedirs = ["tests/test-recipes/*"]
diff --git a/tests/test_api_build.py b/tests/test_api_build.py
index efba89d75d..72442f277e 100644
--- a/tests/test_api_build.py
+++ b/tests/test_api_build.py
@@ -1826,7 +1826,7 @@ def test_downstream_tests(testing_config):
 
 
 @pytest.mark.sanity
-def test_warning_on_file_clobbering(testing_config, capfd):
+def test_warning_on_file_clobbering(testing_config, caplog):
     recipe_dir = os.path.join(metadata_dir, "_overlapping_files_warning")
 
     api.build(
@@ -1844,8 +1844,11 @@ def test_warning_on_file_clobbering(testing_config, capfd):
         config=testing_config,
     )
     # The clobber warning here is raised when creating the test environment for b
-    out, err = capfd.readouterr()
-    assert "ClobberWarning" in err
+    clobber_warning_found = False
+    for record in caplog.records:
+        if "ClobberWarning:" in record.message:
+            clobber_warning_found = True
+    assert clobber_warning_found
     with pytest.raises((ClobberError, CondaMultiError)):
         with env_var("CONDA_PATH_CONFLICT", "prevent", reset_context):
             api.build(os.path.join(recipe_dir, "b"), config=testing_config)