diff --git a/.docker/Dockerfile.unstable b/.docker/Dockerfile.unstable
index 65e3885f..7fcd0443 100644
--- a/.docker/Dockerfile.unstable
+++ b/.docker/Dockerfile.unstable
@@ -11,7 +11,13 @@ RUN curl https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
 RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
 
 RUN apt-get update -yqq && \
-    apt-get install -yqq --no-install-recommends vim nodejs yarn
+    apt-get install -yqq --no-install-recommends \
+    nodejs yarn vim \
+    libjemalloc2 \
+    && rm -rf /var/lib/apt/lists/*
+
+ENV LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
+
 RUN groupadd -g $GID -o $UNAME
 RUN useradd -m -d /opt/app-root -u $UID -g $GID -o -s /bin/bash $UNAME
 RUN mkdir -p /gems && chown $UID:$GID /gems