Any idea to optimize THIS query?

[cedivad]

I'm working hard on the load time of the pages of my script (script is my own, the only thing shared with vbulletin is the database). Expecially, i have big problems with this query:

[SQL]select threadid from thread where forumid=1082 order by dateline desc limit 0, 25;[/SQL]

The query takes about 0.5 sec. The forum (forumid=1082) has about 120'000 topics. The full database has about 5 milion threads.

Executing the query without the "order" takes 0.00 seconds, but i need to order it!

Do someone have some ideas on how to fix this?