Using Fluid.app is there a way to switch tabs periodically?
Developer of Fluid here. This AppleScript is supposed to do what you are asking, but it's causing a crash in the current version of Fluid (1.8.3). I'll look into it.

tell application "&lt;Your Fluid App Name Here&gt;"
    tell browser window 1
        repeat
            set c_ to count of tabs
            set idx_ to index of selected tab
            set idx_ to (idx_ + 1) mod (c_ + 1)
            if idx_ is 0 then set idx_ to 1
            set tab_ to (get tab idx_ of it)
            set selected tab of it to tab_
            delay 20
        end repeat
    end tell
end tell