Qt signals are a one-to-many synchronous/asynchronous intra/inter-thread intra/inter-language dynamic/static message passing mechanism, which figures all that s

Qt signals are a one-to-many synchronous/asynchronous intra/inter-thread intra/inter-language dynamic/static message passing mechanism, which figures all that stuff out by itself by default. 10x slower than a (presumably hot) virtual function call is actually very good for what you're getting.