http://source.roslyn.codeplex.com/#Microsoft.CodeAnalysis/DiagnosticAnalyzer/AnalyzerDriver.cs,951

This should override the base method, not shadow it. (preferably using the standard dispose pattern)
@amcasey points out that it should also skip the loop entirely if lazyNodeActionsByKind has not been initialized.

Also, is that property getter supposed to be thread-safe?
If called on multiple threads, you will leak the pool.
Why not use Lazy<T>?
Are you trying that hard to save allocations?