Hello!
You can edit one of the .lua files in your WAR directory to hide bars. Make sure your user setting ingame is set to show four bars then log out.
Goto your WAR folder/user/interface/AllCharacters/EASystem_ActionBarClusterManager/SavedVariables.lua
Look for a line that says "EA_ActionBar4 =" and "show = true" at lower position.
Just editing "true" to "false" and Save file.
This disable action bar 4
Also create a macro with the following script:
/script TextLogSetEnabled ("Combat", false) TextLogSetEnabled ("UiLog", false)This will turn off combat logging and is a real godsend during laggy situations

Edit: oh, if you're using the BuffThrottle addon disable it, after 1.1 this addon tends to cause more lag than it used to prevent