title: Qt Application Performance vs. WinAPI/MFC/WTL/
body: <p>I'm considering writing a new Windows GUI app, where one of the requirements is that the app must be very responsive, quick to load, and have a light memory footprint.</p>
  
  <p>I've used WTL for previous apps I've built with this type of requirement, but as I use .NET all the time in my day job WTL is getting more and more painful to go back to. I'm not interested in using .NET for this app, as I still find the performance of larger .NET UIs lacking, but I am interested in using a better C++ framework for the UI - like Qt.</p>
  
  <p>What I want to be sure of before starting is that I'm not going to regret this on the performance front. </p>
  
  <p><strong>So: Is Qt fast?</strong></p>
  
  <p>I'll try and qualify the question by examples of what I'd like to come close to matching: My current WTL app is <a href="http://pnotepad.org/" rel="noreferrer">Programmer's Notepad</a>. The current version I'm working on weighs in at about 4mb of code for a 32-bit, release compiled version with a single language translation. On a modern fast PC it takes 1-3 seconds to load, which is important as people fire it up often to avoid IDEs etc. The memory footprint is usually 12-20 mb on 64-bit Win7 once you've been editing for a while. You can run the app non-stop, leave it minimized, whatever and it always jumps to attention instantly when you switch to it.</p>
  
  <p>For the sake of argument let's say I want to port my WTL app to Qt for potential future cross-platform support and/or the much easier UI framework. I want to come close to if not match this level of performance with Qt.</p>