CRX uses old code like jcr base and jcr contentloader from Sling. This old jcr base code has also session pooling which should be turned off in CRX 2.0.
This is caused by a Sling issue SLING-1283.
This issue is fixed by CQ5.3 FeaturePack package #29434. Please raise a DayCare ticket to obtain this package.