I have been using JetBrains for a few months now and have been very satified with the product. It has helped us find many bottlenects in our software.
The latest problem we are running into is the performance of .NET serialization and deserialization. We recently injected a IClientChannelSink and an IServerChannelSink in order to better track the times that serialization and deserializatino is taking and the numbers are terrible. For 4.2mb of data it appears to be taking 15-16 seconds. Here is the problem though, we see different numbers when JetBrains is running vs. when JetBrains is not running.
dotTrace running: 4.2mb takes 15-16 seconds to deserialize
dotTrace not running: 4.2mb takes ~2 seconds
I would assume that dotTrace is adding some overhead, but this seems higher then what I would have expected.