Should you use ReaderWriterLock instead of Monitor.Enter/Exit?

Maybe, carefully.

ReaderWriterLock is used to allow multiple threads to read from a data source, while still granting exclusive access to a single writer thread. This makes sense for data access that is mostly read-only, but there are some caveats.

First, ReaderWriterLock is relatively poor performing compared to Monitor.Enter/Exit, which offsets some of the benefits.

Second, you need to be very sure that the data structures you are accessing fully support multithreaded read access.

Finally, there is apparently a bug in the v1.1 ReaderWriterLock that can cause starvation for writers when there are a large number of readers.