why does my forum keep being slow? im using the latest upgrade 1.2.5
You might want to try optimizing your database in ACP...and maybe doing the recount/rebuild as well. That might help speed it up a bit.
Or maybe you're on a slow server.
If it's like 5 - 30+ second load times then it's most likely your server.
What does it say under "Page generation time" at the bottom of your forum? If it is less than 1 second, then it is your internet connection (or the server's connection) that is to blame. If it is above 1 second, then it is probably your server and you should contact your webhost.