diff --git a/.pipelines/build-job.yml b/.pipelines/build-job.yml
index f883f0b4bb..6ace42272b 100644
--- a/.pipelines/build-job.yml
+++ b/.pipelines/build-job.yml
@@ -124,7 +124,7 @@ jobs:
         displayName: "CMake ${{ parameters.platform }}"
         inputs:
           workingDirectory: "."
-          cmakeArgs: . --fresh -A ${{ parameters.platform }} -DCMAKE_BUILD_TYPE=Release -DCMAKE_SYSTEM_VERSION=10.0.26100.0 -DPACKAGE_VERSION=$(version.WSL_PACKAGE_VERSION) -DWSL_NUGET_PACKAGE_VERSION=$(version.WSL_NUGET_PACKAGE_VERSION) -DSKIP_PACKAGE_SIGNING=${{ parameters.isRelease }} -DOFFICIAL_BUILD=${{ parameters.isRelease }} -DINCLUDE_PACKAGE_STAGE=${{ or(parameters.isRelease, parameters.isNightly) }} -DPIPELINE_BUILD_ID=$(Build.BuildId) -DVSO_ORG=${{ parameters.vsoOrg }} -DVSO_PROJECT=${{ parameters.vsoProject }} -DWSL_BUILD_WSL_SETTINGS=true -DWSL_INCLUDE_SDK_CSHARP=true $(packageInputDirArg)\${{ parameters.platform }}
+          cmakeArgs: . --fresh -A ${{ parameters.platform }} -DCMAKE_BUILD_TYPE=Release -DCMAKE_SYSTEM_VERSION=10.0.26100.0 -DPACKAGE_VERSION=$(version.WSL_PACKAGE_VERSION) -DWSL_NUGET_PACKAGE_VERSION=$(version.WSL_NUGET_PACKAGE_VERSION) -DSKIP_PACKAGE_SIGNING=${{ parameters.isRelease }} -DOFFICIAL_BUILD=${{ parameters.isRelease }} -DINCLUDE_PACKAGE_STAGE=${{ or(parameters.isRelease, parameters.isNightly) }} -DPIPELINE_BUILD_ID=$(Build.BuildId) -DVSO_ORG=${{ parameters.vsoOrg }} -DVSO_PROJECT=${{ parameters.vsoProject }} -DWSL_BUILD_WSL_SETTINGS=true -DWSL_INCLUDE_SDK_CSHARP=true -DWSL_E2E_UNITY_BUILD=ON $(packageInputDirArg)\${{ parameters.platform }}
 
       # Workaround for WSL Settings NuGet restore authentication issue
       - script: _deps\nuget.exe restore -NonInteractive
diff --git a/test/windows/WSLCTests.cpp b/test/windows/WSLCTests.cpp
index 2d09e66462..3028dc87e7 100644
--- a/test/windows/WSLCTests.cpp
+++ b/test/windows/WSLCTests.cpp
@@ -359,38 +359,35 @@ class WSLCTests
     {
         auto sessionManager = OpenSessionManager();
 
-        // Act: list sessions
-        {
-            wil::unique_cotaskmem_array_ptr<WSLCSessionListEntry> sessions;
-            VERIFY_SUCCEEDED(sessionManager->ListSessions(&sessions, sessions.size_address<ULONG>()));
-
-            // Assert
-            VERIFY_ARE_EQUAL(sessions.size(), 1u);
-            const auto& info = sessions[0];
-
-            // SessionId is implementation detail (starts at 1), so we only assert DisplayName here.
-            VERIFY_ARE_EQUAL(std::wstring(info.DisplayName), c_testSessionName);
-        }
-
-        // List multiple sessions.
-        {
-            auto session2 = CreateSession(GetDefaultSessionSettings(L"wslc-test-list-2"));
-
+        auto listDisplayNames = [&]() {
             wil::unique_cotaskmem_array_ptr<WSLCSessionListEntry> sessions;
             VERIFY_SUCCEEDED(sessionManager->ListSessions(&sessions, sessions.size_address<ULONG>()));
 
-            VERIFY_ARE_EQUAL(sessions.size(), 2);
-
             std::vector<std::wstring> displayNames;
             for (const auto& e : sessions)
             {
                 displayNames.push_back(e.DisplayName);
             }
+            return displayNames;
+        };
+
+        auto contains = [](const std::vector<std::wstring>& names, std::wstring_view target) {
+            return std::ranges::find(names, target) != names.end();
+        };
 
-            std::ranges::sort(displayNames);
+        // Act: list sessions
+        {
+            auto displayNames = listDisplayNames();
+            VERIFY_IS_TRUE(contains(displayNames, c_testSessionName));
+        }
+
+        // List multiple sessions.
+        {
+            auto session2 = CreateSession(GetDefaultSessionSettings(L"wslc-test-list-2"));
 
-            VERIFY_ARE_EQUAL(displayNames[0], c_testSessionName);
-            VERIFY_ARE_EQUAL(displayNames[1], L"wslc-test-list-2");
+            auto displayNames = listDisplayNames();
+            VERIFY_IS_TRUE(contains(displayNames, c_testSessionName));
+            VERIFY_IS_TRUE(contains(displayNames, L"wslc-test-list-2"));
         }
     }
 
diff --git a/test/windows/wslc/CMakeLists.txt b/test/windows/wslc/CMakeLists.txt
index 23418d7cbc..4dbc6acc39 100644
--- a/test/windows/wslc/CMakeLists.txt
+++ b/test/windows/wslc/CMakeLists.txt
@@ -18,6 +18,26 @@ set_source_files_properties(${WSLC_TEST_SOURCES}
     COMPILE_FLAGS "/Yuprecomp.h"
 )
 
+# Opt-in unity build for the e2e tests (~2x faster clean recompile; CI enables it).
+option(WSL_E2E_UNITY_BUILD "Unity-batch the wslc e2e test sources" OFF)
+set(WSL_E2E_UNITY_BATCH_SIZE 8 CACHE STRING "Unity batch size for wslc e2e tests")
+
+if(WSL_E2E_UNITY_BUILD)
+    # GROUP mode only batches sources tagged with UNITY_GROUP, so tag e2e sources and leave every other wsltests source untouched.
+    set_target_properties(wsltests PROPERTIES UNITY_BUILD ON UNITY_BUILD_MODE GROUP)
+
+    file(GLOB WSLC_E2E_SOURCES CONFIGURE_DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/e2e/*.cpp)
+    set(_e2eIndex 0)
+    foreach(_e2eSource IN LISTS WSLC_E2E_SOURCES)
+        math(EXPR _e2eGroup "${_e2eIndex} / ${WSL_E2E_UNITY_BATCH_SIZE}")
+        set_source_files_properties(${_e2eSource}
+            TARGET_DIRECTORY wsltests
+            PROPERTIES UNITY_GROUP "wslc_e2e_${_e2eGroup}"
+        )
+        math(EXPR _e2eIndex "${_e2eIndex} + 1")
+    endforeach()
+endif()
+
 # Add include directories needed for WSLC tests.
 target_include_directories(wsltests PRIVATE
     ${CMAKE_SOURCE_DIR}/test
diff --git a/test/windows/wslc/e2e/WSLCE2EPushPullTests.cpp b/test/windows/wslc/e2e/WSLCE2EPushPullTests.cpp
index 9491bb0ba4..d2d38211bd 100644
--- a/test/windows/wslc/e2e/WSLCE2EPushPullTests.cpp
+++ b/test/windows/wslc/e2e/WSLCE2EPushPullTests.cpp
@@ -58,7 +58,7 @@ class WSLCE2EPushPullTests
         auto session = OpenDefaultElevatedSession();
 
         {
-            auto [registryContainer, registryAddress] = StartLocalRegistry(*session, "", "", 15003);
+            auto [registryContainer, registryAddress] = StartLocalRegistry(*session, "", "", 15004);
             auto registryAddressW = string::MultiByteToWide(registryAddress);
 
             // Tag the image for the local registry.