diff --git a/Dockerfile b/Dockerfile
index caa2ee0..6799eef 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,3 +1,4 @@
+# Builder for base osu!
 FROM mcr.microsoft.com/dotnet/sdk:8.0 as builder
 
 ENV DOTNET_CLI_TELEMETRY_OPTOUT 1
@@ -8,7 +9,7 @@ RUN apt-get update \
 ARG OSU_VERSION
 ENV OSU_VERSION=$OSU_VERSION
 
-RUN echo "Downloading and building osu! ${OSU_VERSION}" >&2 \
+RUN --mount=type=cache,target=/root/.nuget/packages --mount=type=cache,target=/root/.local/share/NuGet/http-cache echo "Downloading and building osu! ${OSU_VERSION}" >&2 \
     && git clone --depth=1 --single-branch -b ${OSU_VERSION} https://github.com/ppy/osu \
     && cd osu \
     && dotnet publish \
@@ -19,27 +20,25 @@ RUN echo "Downloading and building osu! ${OSU_VERSION}" >&2 \
         -p:Version=${OSU_VERSION} \
         osu.Desktop
 
-RUN for ruleset in \
-        "Bosu|https://github.com/EVAST9919/bosu" \
-        "Hitokori|https://github.com/Flutterish/Hitokori" \
-        "Karaoke|https://github.com/karaoke-dev/karaoke" \
-        "Mvis|https://github.com/EVAST9919/lazer-m-vis" \
-        "Rush|https://github.com/swoolcock/rush" \
-        "Sentakki|https://github.com/LumpBloom7/sentakki" \
-        "Swing|https://github.com/EVAST9919/lazer-swing" \
-        "Tau|https://github.com/Altenhh/tau" \
-    ; do \
-        repo_url="$(echo $ruleset | cut -d'|' -f2)" \
-        && assembly_name="osu.Game.Rulesets.$(echo $ruleset | cut -d'|' -f1)" \
-        && git clone --depth=1 "$repo_url" ruleset \
-        && cd ruleset \
-        && dotnet build \
-            -c Release \
-            "$assembly_name" \
-        && cp "${assembly_name}"/bin/Release/net*/"${assembly_name}".dll /opt/osu/ \
-        && cd .. \
-        && rm -rf ruleset \
-    ; done
+# Generic builder for rulesets (using onbuild and args)
+FROM mcr.microsoft.com/dotnet/sdk:8.0 as builder-ruleset-generic
+
+COPY ./build-ruleset.sh /usr/local/bin/build-ruleset
+
+FROM builder-ruleset-generic as builder-swing
+RUN --mount=type=cache,target=/root/.nuget/packages --mount=type=cache,target=/root/.local/share/NuGet/http-cache build-ruleset https://github.com/EVAST9919/lazer-swing
+
+FROM builder-ruleset-generic as builder-tau
+RUN --mount=type=cache,target=/root/.nuget/packages --mount=type=cache,target=/root/.local/share/NuGet/http-cache build-ruleset https://github.com/Altenhh/tau
+
+FROM builder-ruleset-generic as builder-bosu
+RUN --mount=type=cache,target=/root/.nuget/packages --mount=type=cache,target=/root/.local/share/NuGet/http-cache build-ruleset https://github.com/EVAST9919/bosu
+
+FROM builder-ruleset-generic as builder-rush
+RUN --mount=type=cache,target=/root/.nuget/packages --mount=type=cache,target=/root/.local/share/NuGet/http-cache build-ruleset https://github.com/swoolcock/rush
+
+FROM builder-ruleset-generic as builder-sentakki
+RUN --mount=type=cache,target=/root/.nuget/packages --mount=type=cache,target=/root/.local/share/NuGet/http-cache build-ruleset https://github.com/LumpBloom7/sentakki
 
 FROM mcr.microsoft.com/dotnet/runtime:8.0
 
@@ -53,6 +52,11 @@ RUN apt-get update \
     && rm -rf /var/lib/apt/lists/*
 
 COPY --from=builder /opt/osu/ /opt/osu/
+COPY --from=builder-swing /dlls/*.dll /opt/osu/
+COPY --from=builder-tau /dlls/*.dll /opt/osu/
+COPY --from=builder-bosu /dlls/*.dll /opt/osu/
+COPY --from=builder-rush /dlls/*.dll /opt/osu/
+COPY --from=builder-sentakki /dlls/*.dll /opt/osu/
 
 RUN adduser --disabled-password --gecos '' osu
 USER osu
diff --git a/README.md b/README.md
index 85de025..f225dcb 100644
--- a/README.md
+++ b/README.md
@@ -6,9 +6,11 @@
 
 Using podman/buildah:
 
-    buildah build --format docker --layers -t osu --build-arg OSU_VERSION=2024.412.1
+    buildah build --format docker --layers -t osu --build-arg OSU_VERSION=2024.412.1 --jobs 0
 
 Change `2024.412.1` to the newest osu! version.
+By changing `--jobs 0` to a positive integer N,
+at most N build stages will be run in parallel.
 
 ### Running
 
diff --git a/build-ruleset.sh b/build-ruleset.sh
new file mode 100755
index 0000000..9ab3175
--- /dev/null
+++ b/build-ruleset.sh
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+RULESET_URL="$1"
+
+git clone --depth=1 "${RULESET_URL}" ruleset
+pushd ruleset
+ASSEMBLY_NAME="$(basename "$(find . -iname '*.sln' -printf '%f\n' | head -n1)" .sln)"
+dotnet build -c Release ${ASSEMBLY_NAME}
+case "${ASSEMBLY_NAME}" in
+	# special build steps can be put here
+	*)
+	mkdir /dlls
+	mv ${ASSEMBLY_NAME}/bin/Release/net*/${ASSEMBLY_NAME}.dll /dlls/
+	;;
+esac
+popd
+rm -rf ruleset