The debugger would hang if a lot of complex objects (like the result of Get-Process) were sent to the pipeline.
The problem was that some code had been introduced to return the result of a PowerShell script execution from the host process back to visual studio so it could be used to annotate code for profiling purposes. When an object was returned from the pipeline, it would be serialized to CliXml and sent to VS. The problem is when complex objects go through the serialization process that can cause an infinite loop in the serializer. This results in the host process hanging while attempting to send the result back to VS.
The code that was introduced for serialization has simply been reverted.