With an Alt+P on your keyboard, subsequent forum actions should put up a timing string just under the forum banner (for me, on the right) and if you click on the timing, you’ll see a popup window with some stats.
That’s about the same as mine, running with 1G of RAM. I have 2k topics, 15k posts, 500+ signups.
What’s the history of your Discourse? I dimly recall a time in the past when one was supposed to create an index for some table for performance reasons.
What about plugins? Can you run actions in safe mode to see if they run any quicker?