Actually not. What I'm trying to say is that UNU fired during "normal operation" are enough to cause high CPU usage peaks with certain addons. There was a clear link between *any* fired UNU and freezes and I was able to cause such thing by simply mounting/dismounting. That is quite uncomfortable enough. I'm sure adding title rotations on top of this should be terrible.
In other words, do not blame only title rotation addons.
Asshats running those 'change your title every 5 seconds' addons will also destroy your raid frame performance if UNU is still registered.
At the point of testing what was caused the issue, I added debug code to print every UNU, RRU and PMC events. During a 5-minute test period, the only UNU events I've seen were about raidpetX units. There was no need for title "rotator" to cause freezes.
Some weeks ago I experienced noticeable freezes (e.g. almost a second) in Alterac. Everything was running fine beside that. I've looked up for the addon that caused this (by disabled them one by one until the freezes ceased) and found that Grid was responsible for it. I enabled all addons but Grid and everything was ok. Then I enabled Grid and freezes started to happen again. Unregistering UNU in Grid frame initialization fixed the issue. IMO not all unit frames are impacted the same way by UNU spam but Grid is very bad at it.
oUF does use what you tell it to use, e.g. SecureGroupHeaderTemplate if you want to. In this case, oUF takes care of setting up the header to apply your layout to the created unit frames. You still have to layout your different headers. Sample code:
-- define and select your oUF style here
-- single unit
local player = oUF:Spawn("player", "oUF_MyPlayerFrame")
-- party group
local party = oUF:Spawn("header", "oUF_MyParty")
party:SetManyAttributes("showParty", true, "groupFilter", 1)
The main trouble with oUF is that it lacks some comprehensive docs (or an easy way to find them ; I couldn't). Once you understand how it works, it actually simplifies things, as it provides a lot of simple frame "elements" to add to your layout.