I understand where you are coming from Niels, but several things can be done to optimize performance. If you are are writing to Talk's database, the delay is almost not important since the routine (when adding news, blog entry, or app) is called the same time when the entry is saved to maemo.org's server. And as I have mentioned, you can even call a Talk page so I can create the thread on my side.
Now if you are concerned about multiple queries on Talk's database then don't run queries. Let me feed you data and render them asynchronously (ajax), just after the whole page is rendered. I see that you are running jQuery on maemo.org. It should work nicely.
With regards to your question of rendering comments, no, we shouldn't render the same comments in maemo.org from Talk. The only info you need to display is the number of comments (e.g. 25 comments.) from the corresponding thread at Talk. A link on the number of comments will redirect the user to the discussion in Talk. Before we talk about how slow it will be, trying it out first might be worth a shot.