diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 68c4804..f67886e 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -13,13 +13,12 @@ env:
 
 jobs:
   test:
-    name: Test on ${{ matrix.os }} using Rust ${{ matrix.rust }} with bindgen features '${{ matrix.cargo_features }}'
+    name: Test on ${{ matrix.os }} using Rust ${{ matrix.rust }}'
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-latest]
-        rust: [stable, nightly]
-        cargo_features: ['']
+        os: [windows-latest]
+        rust: [nightly]
 
     steps:
     - uses: hecrj/setup-rust-action@v2
@@ -39,38 +38,56 @@ jobs:
       run: echo "LIBCLANG_PATH=C:\Program Files\LLVM\bin" >> $GITHUB_ENV
       shell: bash
 
-    - name: Cargo fmt
-      run: cargo +${{ matrix.rust }} fmt --all -- --check
-      if: matrix.os == 'ubuntu-latest' && matrix.rust == 'nightly'
+    - name: Run c roaring
+      if: matrix.os == 'windows-latest'
+      run: |
+        clang --version || true
+        clang -O3 -o c_roaring.exe roaring_fast_or.c
+        ./c_roaring.exe
+
+      shell: bash
 
-    - name: Cargo clippy
-      run: cargo +${{ matrix.rust }} clippy --all-targets --workspace --features "${{ matrix.cargo_features }}"
-      if: matrix.os == 'ubuntu-latest' && matrix.rust == 'nightly' && matrix.cargo_features != ''
+    - name: msvc c roaring
+      if: matrix.os == 'windows-latest'
+      run: |
+        $env:LIB="C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\lib\x64;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\atlmfc\lib\x64;C:\Program Files (x86)\Windows Kits\10\lib\10.0.22621.0\ucrt\x64;C:\Program Files (x86)\Windows Kits\10\lib\10.0.22621.0\um\x64;"
+        $env:PATH="C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\bin\HostX64\x64;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\bin\HostX64\x64;C:\Program Files (x86)\Windows Kits\10\bin\10.0.22621.0\x64;C:\Program Files (x86)\Windows Kits\10\bin\x64;D:\a\croaring-rs\croaring-rs\target\release\deps;D:\a\croaring-rs\croaring-rs\target\release;C:\Users\runneradmin\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\x86_64-pc-windows-msvc\lib;C:\Users\runneradmin\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\bin;C:\Program Files\PowerShell\7;/c/Users/runneradmin/.cargo/bin;C:\Program Files\MongoDB\Server\5.0\bin;C:\aliyun-cli;C:\vcpkg;C:\Program Files (x86)\NSIS\;C:\tools\zstd;C:\Program Files\Mercurial\;C:\hostedtoolcache\windows\stack\2.13.1\x64;C:\cabal\bin;C:\\ghcup\bin;C:\mingw64\bin;C:\Program Files\dotnet;C:\Program Files\MySQL\MySQL Server 8.0\bin;C:\Program Files\R\R-4.3.2\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\SeleniumWebDrivers\EdgeDriver\;C:\SeleniumWebDrivers\ChromeDriver;C:\Program Files (x86)\sbt\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\bin;C:\Program Files (x86)\pipx_bin;C:\npm\prefix;C:\hostedtoolcache\windows\go\1.20.13\x64\bin;C:\hostedtoolcache\windows\Python\3.9.13\x64\Scripts;C:\hostedtoolcache\windows\Python\3.9.13\x64;C:\hostedtoolcache\windows\Ruby\3.0.6\x64\bin;C:\Program Files\OpenSSL\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\8.0.402-6\x64\bin;C:\Program Files\ImageMagick-7.1.1-Q16-HDRI;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\ProgramData\Chocolatey\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Program Files\dotnet\;C:\Program Files\PowerShell\7\;C:\Program Files\Microsoft\Web Platform Installer\;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn\;C:\Program Files\Microsoft SQL Server\150\Tools\Binn\;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\;C:\Program Files\Microsoft SQL Server\130\DTS\Binn\;C:\Program Files\Microsoft SQL Server\140\DTS\Binn\;C:\Program Files\Microsoft SQL Server\150\DTS\Binn\;C:\Program Files\Microsoft SQL Server\160\DTS\Binn\;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\TortoiseSVN\bin;C:\Program Files\CMake\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.8.7\bin;C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code;C:\Program Files\Microsoft SDKs\Service Fabric\Tools\ServiceFabricLocalClusterManager;C:\Program Files\nodejs\;C:\Program Files\Git\cmd;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\Program Files\GitHub CLI\;c:\tools\php;C:\Program Files (x86)\sbt\bin;C:\Program Files\Amazon\AWSCLIV2\;C:\Program Files\Amazon\SessionManagerPlugin\bin\;C:\Program Files\Amazon\AWSSAMCLI\bin\;C:\Program Files\Microsoft SQL Server\130\Tools\Binn\;C:\Program Files\LLVM\bin;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\.cargo\bin;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps"
+        $env:INCLUDE="C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\atlmfc\include;C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\ucrt;C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um;C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\cppwinrt;C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\winrt;C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\shared;"
+        & "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\bin\HostX64\x64\cl.exe" -nologo -MD -O2 -Brepro /Fe:roaring_fast_or.exe /Zi /DEBUG ./roaring_fast_or.c
+        echo "running"
+        ./roaring_fast_or.exe
+        echo "$LASTEXITCODE"
+      continue-on-error: true
 
-    - name: Cargo clippy
-      run: cargo +${{ matrix.rust }} clippy --all-targets --workspace
-      if: matrix.os == 'ubuntu-latest' && matrix.rust == 'nightly' && matrix.cargo_features == ''
 
-    - name: Build
-      run: cargo +${{ matrix.rust }} build --features "${{ matrix.cargo_features }}"
-      if: matrix.cargo_features != ''
+      # - name: Cargo fmt
+    #   run: cargo +${{ matrix.rust }} fmt --all -- --check
+    #   if: matrix.os == 'ubuntu-latest' && matrix.rust == 'nightly'
 
-    - name: Build
-      run: cargo +${{ matrix.rust }} build
-      if: matrix.cargo_features == ''
+    # - name: Cargo clippy
+    #   run: cargo +${{ matrix.rust }} clippy --all-targets --workspace
+    #   if: matrix.os == 'ubuntu-latest' && matrix.rust == 'nightly'
 
-    - name: Test
-      run: cargo +${{ matrix.rust }} test --features "${{ matrix.cargo_features }}"
-      if: matrix.cargo_features != ''
+    # - name: Build
+    #   run: cargo +${{ matrix.rust }} build
 
-    - name: Test
-      run: cargo +${{ matrix.rust }} test
-      if: matrix.cargo_features == ''
+    # - name: Test
+    #   run: cargo +${{ matrix.rust }} test
 
     - name: Benchmark
       if: matrix.rust == 'nightly'
-      run: cargo +${{ matrix.rust }} bench
+      run: cargo +${{ matrix.rust }} bench -vv -- 'or/fast'
+      continue-on-error: true
 
-    - name: Minimal versions
-      if: matrix.rust == 'nightly'
-      run: cargo +${{ matrix.rust }} -Zdirect-minimal-versions test
+    - name: Archive artifacts
+      if: matrix.os == 'windows-latest'
+      uses: actions/upload-artifact@v4
+      with:
+        name: built artifacts
+        path: |
+          *.exe
+          target/release/*.exe
+
+    # - name: Minimal versions
+    #   if: matrix.rust == 'nightly'
+    #   run: cargo +${{ matrix.rust }} -Zdirect-minimal-versions test
diff --git a/croaring-sys/build.rs b/croaring-sys/build.rs
index b76e896..26dd53b 100644
--- a/croaring-sys/build.rs
+++ b/croaring-sys/build.rs
@@ -6,6 +6,7 @@ fn main() {
     println!("cargo:rerun-if-env-changed=ROARING_ARCH");
 
     let mut build = cc::Build::new();
+    let compiler = build.get_compiler();
     build.file("CRoaring/roaring.c");
 
     if let Ok(target_arch) = env::var("ROARING_ARCH") {
@@ -13,5 +14,7 @@ fn main() {
     }
 
     build.flag_if_supported("-Wno-unused-function");
+    println!("cargo:warning=compiler {compiler:#?}");
+    println!("cargo:warning=build: {build:#?}");
     build.compile("roaring");
 }
diff --git a/croaring/src/bitmap/imp.rs b/croaring/src/bitmap/imp.rs
index b946e8e..3ad2bdb 100644
--- a/croaring/src/bitmap/imp.rs
+++ b/croaring/src/bitmap/imp.rs
@@ -491,12 +491,28 @@ impl Bitmap {
     #[doc(alias = "roaring_bitmap_or_many")]
     #[must_use]
     pub fn fast_or(bitmaps: &[&Bitmap]) -> Self {
+        #[cfg(windows)]
+        {
+            extern "C" {
+                pub fn croaring_hardware_support() -> std::ffi::c_int;
+            }
+            eprintln!("hardware support: {:x}", unsafe {
+                croaring_hardware_support()
+            });
+        }
         let mut bms: Vec<*const ffi::roaring_bitmap_s> = bitmaps
             .iter()
             .map(|item| ptr::addr_of!(item.bitmap))
             .collect();
 
-        unsafe { Self::take_heap(ffi::roaring_bitmap_or_many(bms.len(), bms.as_mut_ptr())) }
+        eprintln!("{bms:#?}");
+
+        unsafe {
+            Self::take_heap(dbg!(ffi::roaring_bitmap_or_many(
+                bms.len(),
+                bms.as_mut_ptr()
+            )))
+        }
     }
 
     /// Compute the union of 'number' bitmaps using a heap. This can
diff --git a/roaring_fast_or.c b/roaring_fast_or.c
new file mode 100644
index 0000000..a5a0c0a
--- /dev/null
+++ b/roaring_fast_or.c
@@ -0,0 +1,20 @@
+#include "croaring-sys/CRoaring/roaring.c"
+
+int main(void) {
+    roaring_bitmap_t *r1 = roaring_bitmap_of(2, 500, 1000);
+    roaring_bitmap_t *r2 = roaring_bitmap_of(2, 1000, 2000);
+
+    fprintf(stderr, "Hardware support: %#x\n", croaring_hardware_support());
+
+    const roaring_bitmap_t *bitmap_arr[2] = {r1, r2};
+    fprintf(stderr, "Going to or many\n");
+    for (int i = 0; i < 10000; i++) {
+        roaring_bitmap_t *r = roaring_bitmap_or_many(2, bitmap_arr);
+        roaring_bitmap_free(r);
+    }
+
+    fprintf(stderr, "Got done\n");
+
+    roaring_bitmap_free(r2);
+    roaring_bitmap_free(r1);
+}
\ No newline at end of file