CachingEntryCollector ineffective if number of accessed policies exceeds cache size

The CachingEntryCollector's cache (LRUMap, max size: 1000) seems to become ineffective in case there are more than 1000 ACEs present in the repository. Since access to the cache is synchronized, many threads are basically blocked, waiting to get access to the cache.

Java callstack:
at org/apache/jackrabbit/core/security/authorization/acl/CachingEntryCollector.getEntries(CachingEntryCollector.java:99(Compiled Code))
at org/apache/jackrabbit/core/security/authorization/acl/EntryCollector.collectEntries(EntryCollector.java:134(Compiled Code))
at org/apache/jackrabbit/core/security/authorization/acl/CompiledPermissionsImpl.canRead(CompiledPermissionsImpl.java:250(Compiled Code))
at org/apache/jackrabbit/core/security/DefaultAccessManager.canRead(DefaultAccessManager.java:251(Compiled Code))
at org/apache/jackrabbit/core/ItemManager.canRead(ItemManager.java:426(Compiled Code))
at org/apache/jackrabbit/core/ItemManager.createItemData(ItemManager.java(Compiled Code))
at org/apache/jackrabbit/core/ItemManager.getItemData(ItemManager.java:379(Compiled Code))
at org/apache/jackrabbit/core/ItemManager.itemExists(ItemManager.java:292(Compiled Code))
at org/apache/jackrabbit/core/ItemManager.itemExists(ItemManager.java:464(Compiled Code))
at org/apache/jackrabbit/core/session/SessionItemOperation$1.perform(SessionItemOperation.java:49(Compiled Code))
at org/apache/jackrabbit/core/session/SessionItemOperation$1.perform(SessionItemOperation.java:46(Compiled Code))
at org/apache/jackrabbit/core/session/SessionItemOperation.perform(SessionItemOperation.java:187(Compiled Code))
at org/apache/jackrabbit/core/session/SessionState.perform(SessionState.java:200(Compiled Code))
at org/apache/jackrabbit/core/SessionImpl.perform(SessionImpl.java:355(Compiled Code))
at org/apache/jackrabbit/core/SessionImpl.itemExists(SessionImpl.java:751(Compiled Code))