Update README.md

Author: bitfaster

README.md

@@ -11,10 +11,8 @@ High performance, thread-safe in-memory caching primitives for .NET.
 
 | Class |  Description |
 |:-------|:---------|
-| ClassicLru       | Bounded size LRU based with strict ordering.<br><br>Use if ordering is important, but data structures are synchronized with a lock which limits scalability. |
-| ConcurrentLru       |  Bounded size pseudo LRU.<br><br>For when you   want a ConcurrentDictionary, but with bounded size. Maintains psuedo order, but is faster than ClassicLru and not prone to lock contention. |
-| ConcurrentTlru        | Bounded size pseudo LRU, items have TTL.<br><br>Same as ConcurrentLru, but with a [time aware least recently used (TLRU)](https://en.wikipedia.org/wiki/Cache_replacement_policies#Time_aware_least_recently_used_(TLRU)) eviction policy. |
-| FastConcurrentLru/FastConcurrentTLru      | Same as ConcurrentLru/ConcurrentTLru, but with hit counting logic eliminated making them  10-30% faster.   |
+| ConcurrentLru       |  Bounded size pseudo LRU.<br><br>A drop in replacement for ConcurrentDictionary, but with bounded size. Maintains psuedo order, with better hit rate than a pure Lru and not prone to lock contention. |
+| ConcurrentTlru        | Bounded size pseudo LRU, items have TTL.<br><br>Same as ConcurrentLru, but with a [time aware least recently used (TLRU)](https://en.wikipedia.org/wiki/Cache_replacement_policies#Time_aware_least_recently_used_(TLRU)) eviction policy. If the values generated for each key can change over time, ConcurrentTlru is eventually consistent where the inconsistency window is the TTL. |
 | SingletonCache      | Cache singletons by key. Discard when no longer in use. <br><br> For example, cache a SemaphoreSlim per user, where user population is large, but active user count is low.   |
 | Scoped<IDisposable>      | A threadsafe wrapper for storing IDisposable objects in a cache that may dispose and invalidate them. The scope keeps the object alive until all callers have finished.   |