+* Issue #240: Based on real-world performance measures against 5.4, zip
+ manifests are now cached in all circumstances. The
+ ``PKG_RESOURCES_CACHE_ZIP_MANIFESTS`` environment variable is no longer
+ relevant. The observed "memory increase" referenced in the 5.4 release
+ notes and detailed in Issue #154 was likely not an increase over the status
+ quo, but rather only an increase over not storing the zip info at all.