[ehrwien]

Is it intended behaviour that if I use the "My Posts" search function under the "My Activity" menu at the top of the page, that it does not start a new search if I search again in a certain amount of time (seems to me like it's at least half an hour?), but rather delivers the previous search result with the same searchid, which might be outdated at that time?

If I go to "Advanced Search" and enter my own username there, it will actually do an up-to-date search and deliver the correct, current results.

[Adam]

That's correct, and also the intended behavior for searches. You can add &nocache=1 to a personal search URL to force it to get the latest list of posts.