Ah ok, gotcha! Thanks for the info.
If you suspect there may be a bug or something with the client go ahead and report it over on the #support:bug-report forums. Technical Support forums are here for troubleshooting issues and we can’t address bugs. Although I will say that I haven’t seen any widespread reports of stuttering with the WoW client, so if you have details (programs running, specific settings, ways to get the stutter to happen) that info would be useful for the bug report in order to try and reproduce the issue.