Install yarn See it in action yarn test I'm lazy, how do I investigate why it breaks ? GENERATE_HEAP_DUMP=true HEAPDUMP_INTERVAL=3000 yarn test Then load the heapdumps in chrome dev tools and you can compare them Tweaks Edit the max_old_space_size in package.json to have more or less time before the out of memory. Where can I help webpack/webpack#6929