I went to Cyrodiil on my Healer to get some AP and whenever I get a lot of XP and/or AP in Cyrodiil I eventually get these momentary freeze-ups upon gaining more, but things return to normal after I obtain it. Of course it happens every single time I gain XP and AP at that point. Well, it's Cyrodiil we all know what to expect there. However...
After leaving Cyrodiil with my Healer I went to Wrothgar to do a daily quest. All the XP I earn from mobs in Wrothgar are causing those freeze-ups too! Relogging will fix it of course, but I just wanted to mention this in case it has any relevance of any sort to fixing Cyrodiil lag.
Guildmaster of Power With Numbers in PS4 NA Server's Aldmeri Dominion.
Proud Founder of the Yaysay cult! DOWN WITH THE NAYSAY CULT!! #ToxicRemedy