I’ve been participating in Cyrodiil PVP for many years. During that time, I’ve been in several mid to high tier PVP raid guilds, and also spent plenty of time joining up with PUG groups and small teams.
Up until recently, the cap on group sizes was 24. To me, this was a perfect number. MOST organized groups that I've seen run around in Cyrodiil tend to run somewhere between 15 and 20 people. Now, with the size reduced to 12, those groups are a thing of the past. And this is having a negative impact on GUILDS.
To me, GUILDS are the CORE of any MMO. It's what makes the community. If you think zone chat is "community chat", I invite you to spend 30 minutes reading the zone chat in Cyrodiil. There is very little "community" about it. But the effect the 12 man cap has on guilds is that it is very easy for guild members to be excluded from the fun of Cyrodiil PVP. If you have 16 players who regularly raid together... now you've got either two teams of 8, or a 12 man and a 4 man. The 4 man team, trying to run around with the 12 man, is going to get butchered. Not enough healing possible in such a small group, to counter the massive damage from many 12 man group stacks you come up against. So this is very bad for guild morale, in my opinion.
Funny enough, the reported REASON for this change (as indicated by ZOS) was to improve the performance of the Cyrodiil zone. The thing is, I have NOT seen this vast performance increase from this change. Instead, I see groups being split apart. I have seen guild leaders leaving. I have seen upset among players. Gray Host is still unplayable during prime time, unless you don't mind the enormous lag and crashing. So I ask: What was the point of this change if it didn't actually fix the problem it was touted as fixing?
What I have seen is this: In ANY region within Cyrodiil, when the total number of players is LOW, it performs well. But once you get 50-100 players in a that region, it lags and performs horribly. Skill delays. Ultimate delays. Perma-lock downs. Crashes. All the same stuff that happened before this "fix".
So the 12 man cap did not alleviate the core of the problem: Too many players in a condensed space within the zone. What problem did the 12 man cap actually fix? Were people complaining about the size of "zergs"? Because the 12 man cap did NOT change that at all. Just hang out at Ales for a while on CP or Standard and you'll see what I mean. And once that region gets too many players, it lags. It doesn't have anything to do with group size. It merely has to do with the total amount of players in that space at the same time.
My suggestion is this:
1. Remove the 12 man cap and go back to 24 man as a maximum.
2. Change it so that if you are in a group of 6 or less, your heals affect your own group first, and then up to 6 other players OUTSIDE your group.
3. Groups of 7 or more have their heals consolidated to group only.
4. Figure out exactly how many people can be in a condensed region before the server starts to lag. And I recommend ZOS devs themselves playing in Cyrodiil during prime time, to get the true feel of what is happening. Go to the busy fights and try using skills. Of course still look at your server stats, but it's also important to experience the game play itself, in addition to those stats. Then get a count of how many players are there once the lag starts. Now you've got something to work with.
5. Based on #4, either upgrade the server hardware (PREFERRED) or somehow work out a way to limit the amount of players in each region. Possibly this could be done with strategically placed gates which have a "load screen" to walk through. Gates could have QUEUES just like the entire Cyrodiil zone has a queue when it is full. I know this would suck for some people, but as long as there's a way to get some extra people through who are grouped, this could potentially be OK. Make it a soft cap, and allow players through the gate who are already in group with those who have gotten into the region before them. CAUTION: If the limit is too small, it will cause HUGE upsets.
Those are my thoughts on this thing. Biggest thing I have a problem with is group size cap. Go back to 24, since it didn't make a bit of difference on the number of players participating in a hot region at the same time. And that is when the lag shows up. Every time.