ReaderWriterLockSlim vs. Monitor

Question

I have an IDictionary implementation that internally holds n other Dictionary and distributes that insertion

Answer 1

I'm no guru, but my guess is that RWLS is more geared towards heavy contention (e.g., hundreds of threads) whereas Monitor is more attuned towards those one-off synchronization issues.

Personally I use a TimerLock class that uses the Monitor.TryEnter with a timeout parameter.