Speed of Ebay API on C#

[IFmatilde]

I have developed a C# ebay app that goes and search ebay items by keywords using the ebay finding API.I have done one in WinForms and one in ASP.NET(the same functionality on both).Even only 10000 items can be retrieved( the first 10000 actually since you have max 100 pages ,max 100 items per page).But the WinForms App takes about 6 min to download all the items and the ASP.NET takes about 4 and a half minutes.I have a friend who uses the Ebay Blackthorne software and he said that uploading 30000 items with it takes about 2-3 days(though i am aware that it is implemented using the trading API).So my question is how to speed up your ebay app on the windows platform- is multi-threading gonna make it faster(it is a web bound I/O after all) ,is the trading api faster than the finding api?When one uses the ebay app for android even with 3g connection,when you type search expressions it appears to show everything almost instantaneous.Could thisr be done in C#?I havent downloaded the Ebay Windows SDK ,but directly am adding web reference to my project.Also the app is running in Virtual Box and my internet speed (Virgin broadband) is download :up to 1MB/s(megabyte) and upload :up to 100KB/s.........What i do is obtain the information about the items ,convert it to string and append it in a rich text box,which becomes visible after all of the search has completed.......Again, any specifics of how to speed up the up and elaboration on how native ebay app are working would be greatly appreciated>>>