First of all, thanks for the great CnPack.
Code completion is very nice feature and I use it a lot. I like that i don't need to type Ctrl+Space to invoke it. But sometimes this feature hangs the whole application because Code completion is doing some operations (probably filling a string list) and further typing is impossible until it finishes the job. So my suggestion would be to fill code completion list in the separate background thread and display results box only when all the job is done, because I don't need results while I am typing something. That shouldn't be hard to implement in my opinion and it would greatly speed up productivity.