Fastest in-memory cache for .NET
$ dotnet add package Jitbit.FastCache6x-10x faster alternative to MemoryCache
Bascially it's just a ConcurrentDictionary with expiration.
This lib uses Environment.TickCount which is 26x times faster tham DateTime.Now. But TickCount is limited to Int32 overflow. That is why you cannot cache stuff for more than ~25 days (2.4 billion milliseconds).