Hi, I've been doing some testing with implementing a semi lock-free Signals/Slots library. Basically: 1. emits are lock-free thanks to atomic shared_ptr's/other atomic operations. 2. Only a single writer is allowed at a time, uses a mutex for locking. The primary goal is to improve low and no slot-count signal emit performance. In tests, I have been able to get substantial performance boosts (~2 to 5 times) on low slot-count signals, approaching the same performance as signals2 in low-contention (basically, single thread testing). I haven't tested high emit contention performance, though I suspect this library will excel quite well here because there is no locking on emit. The test implementation is still incomplete, and notably uses many C++11 features, though I don't think any of features I'm using can't be ported one way or another for C++03 support. Even if the library isn't used in full, some of the ideas might be implemented into the existing Signals2 library. link: https://github.com/helloworld922/signals3