WotLK Spell casting Bar does not appear when casting and lags.

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A couple friends and I just started playing on this server (Lordoreon) and we are experiencing the same issue. When casting a spell, the casting bar does not appear and sometimes lags when casting, as well as when looting sometimes too.

We came from DalaranWow, so we already had the 3.3.5a game client installed. However, I don't think the game client has anything to do with this issue.
Regardless, we are bran new players and would like to play without having this issue of course.

Please help!

Thanks,
Matt