C# Project Code Optimisation (Game autoupdate software)

Hi, I have coded an application in C# that grabs data from URL, validates game version and then starts a game if it is up to date. If it isn't, it retrieves a list of patches, downloads them and extracts. I have got certain issues with the code, for instance: two of my custom methods (custom MessageBox and custom DialogResult window) are frozen when called (sometimes), so it is required to rewrite them to either use threads or any other method you think is appropriate that wouldn't cause UI thread to be blocked. Additionally, one of the async methods will never stop executing or will wait until all threads are stopped before it cancels its work, so user is left waiting for a long time. Ultimately, I would like you to go through the code and optimise it so that there are no memory leaks and to make the software run faster & smoother. This project should ideally take you less than 4 hours, as the main code is working and just improvements are needed.