@Vlad-Nirky Its not an impression, the app is inefficient in its current state, optimizations are needed. The perception will vary depending on the amount of whatsapp data you receive. Its a combination of having the backend written in python (which means that on receiving new events, a python process is created to process it on the fly) and the qml frontend re-rendering on each event that emits a qml update. So for example receiving a new chat means re-rendering the whole chat list.
Not too worried about it yet, but something for me to look in the future. I'm not 100% decided on how this app will manage its data so not gonna waste time optimizing something that might change. Probably will get back to this once the app support all possible Whatsapp events / message types, which will give clarity on how to model everything.