You miss the point: .NET can perfom good. Winforms NOT. Winforms render by software and not take advantage of nothing about HW aceleration. So a server-side code like ASP.NET app can perform well because a)Is under a scalable plataform (=web server) b)Is made in scalable way (=stateless) c)Render simply strings (=HTML code).

In the other hand, render native app is another story. Winform is so bad (about performance, no so bad aboud desing) that is deprecated by next OS release (how much time you heard that a solution is deprecated 4-7 YEARS BEFORE that can be real??????)

So, in the setup that the poster stated, a WINFORM app can run very, very bad or run simply bad, depend how much complex is more related to hoe complicated is the render and not so much about logic code(that its, use only basic Winform controls or use things like complex grids?)

In the end, compare the performance of server side agains client side is useless because are diferent monster. For that reason, close to any thing, include interpreted stuff (like ASP) and any language like Java, Perl, PHP, bla (no matter if compile or not )perform enough good in SERVER code because desing (also, a memory manager help a lot).

In a computer with 1 G, 512 RAM, performance of Winform is still inferior..is possible "feel" that is enough good, right, but is clearly inferior.