After updating to v2.15.0 eslint started running out of memory on our fairly large project.
I was able to reproduce something similar when running the plugin against a dozen copies of lodash-es. I can create a repro case, but it's rather trivial.
One rule is enough to see the difference between v2.14.0 and v2.15.0:

plugins:
  - import

rules:
  import/default: 2

This seems to be caused by 05c3935. I've run some memory profiles, but I can't pinpoint the exact source of the leak other than that it seems to originate in ExportMap.js. It's possible that the leak was always there, but extra parsing and memory allocations made it more evident.