I was actually planning on suggesting something like this as well. Infected at the moment are too weak, and you don't just fix it by making them take an extra bullet since the player can still jump on literally anything and deal with them.
I get that by increasing a number of infected in a small area would result in performance drop and other issues, but it could be optimized. Now, I don't know if it could be optimized with coding (I never modded for DayZ so..), but there are ways to trick this 'system' and go around whole performance drop issues.
For example, what I was thinking of is adding different kinds of infected and/or even adding "mutants" (not like before when we had 'immortal' heavies). Taking inspiration from other games (Left4Dead2; S.T.A.L.K.E.R; Dying Light; etc.) and/or movies (Walking Dead; World War Z; Train to Busan; etc.). There are plenty of mods on the workshop to cover these and as for the ones - missing, it is possible to make them from scratch, using free resources on the web if needed.
Infected path-finding and spawn rates/locations could be worked on.
For example: Altering their path-finding would mean that they wouldn't roam off that easily and it would be harder for player to avoid their attention. This would make it harder for the player to just run around different areas and would produce the "horde-like" effect without even increasing the number of infected that spawn in the area therefore not impacting the performance.
As for spawn rates/locations, adding a random infected spawn location on a highway, for example, and altering their path-finding so that unless their attention is caught by players/wildlife, small groups of infected would follow the road in a specific direction. This would also produce the "horde-like" effect like in The Walking Dead series, while it wouldn't impact the performance as long as it's well executed.
Why do something like this? The server is perfectly fine without these 'upgrades':
A good portion of the world is breaking apart because of the infection, but if 'the infection' is same everywhere as in "in-game Chernarus", then It would've been, realistically, dealt with a long time ago...
More in-game content:
Lets set a scene for example, sometimes the ordinary RP gets a bit dull and slow-paced. Nothing is going on and you and your mates are just sitting around a campfire, all of you are running out of dialogue options since you already know everything about each other and running to the nearest RP hub is a no because at that moment the server population is low and nobody is around. If we had different variations of infected + hordes, it would allow for some good PvE content. Imagine you and your mates assembling a squad to go hunting for a specific kind of infected or going and clearing an area of an entire horde. Some people would get such experiences, that they would even PK if their character dies in an interesting way in scenarios that these small additions could produce.
What would be an excuse for different types of infected appearing suddenly out of nowhere in the game?
There are different options to deal with this sort of issue:
Adding another wave of the infection mutating, causing infected to grow in to different forms;
Pulling a good ol' western classic "The evil Russians and their evil experiments in their evil labs for evil purposes in the name of their evilness";
Acting as if they were always in game.
Pros and Cons of this idea:
Providing more in game content;
Possibility of PvE;
Giving the old players something new to try out and attracting new players (having in mind that not many RP servers have this option with infected);
Allowing new types of stories and experiences to develop;
Many players sometimes act as If there is no apocalypse going on, implementing this idea would potentially change that as the players would have to become more aware of their surroundings. Since then, on top of hostilities that the player may have with other players/factions, he/she would have another concern to worry about.
If executed poorly, performance drop is guaranteed;
Would take a considerable amount of work to make this a reality;
Even if executed correctly, adding more different mods on top of each other would certainly result in some bugs/glitches here and there, especially when working with in-game AI path-finding.
Some players definitely share different opinions on this topic and would most likely rather not change anything.
Tbh, I'd love to see Orsis T-5000 in game again (It was present while the MSFC mod was present, using the .308 round). It's a modern Russian Sniper rifle, mainly used by Spetsnaz FSB forces.
There are plenty of mods on the workshop to cover this. In case you''d want it as an original thingy, there is plenty of Free 3D models of it on the web so it can be easily remodeled on to a in-game Winchester sniper rifle.