My customer Mahle deploys 802.1x in his network.
On 2960-S with SW 15.2.2.E8 he observes regularily low memory on a stack of four switches if the number of 802.1x sessions reaches about 120.
Or in other words: With 30-40 802.1x sessions, everything is fine, but with 120 sessions, the switch becomes irresponsive.