Can you try increasing the RAM assigned to the game?
Open the game install folder (Right click the game in steam > Manage > Browse Local Files)
Find the ProjectZomboid64 json file and open it in a text editor.
Find the line "-Xmx3072m" and change it to "-Xmx5G" and see if that helps?
An important detail I forgot to add: Visual Damage and Destruction System
In 1993, during the panic of the Knox Event, these buses would have been used as battering rams or get jammed in chaotic traffic. Therefore, their spawn condition should reflect this:
Visual Wear: They should rarely spawn in perfect condition. I expect to see them with massive dents, detached or bent accordion doors, shattered safety glass windows, and heavy scratches all over the chassis.
Scrap Value: A completely destroyed bus shouldn't just be an obstacle; it should be a goldmine for Metalworking. Players could harvest a huge amount of metal sheets, scrap metal, and heavy pipes from a wrecked transit bus, making them useful even if they can't be repaired.
One thing i forgot to mention, among the MP5 a carbine should also follow. Yes, the m16 is capable since its still an AR-15 platform but i don't know... i just really like the concept of also having a carbine and not a full rifle. Plus, i would've really needed it back in modded B41 when clearing bunkers. I still get spikes in my heartrate even thinking about how the zombies got too close for comfort and the barrel of the gun was right at their chest basically. That tiny gap you'd be able to get with the carbine would be beneficial i imagine. (im mostly thinking about something like the colt 733)
Rifles such as Colt 723 was the standard for Delta force in the 80's and 90's. Just how could would it be to find a special forces operators gun in the game? Or the Colt 727 which was used by Navy SEALS and the 75th Rangers supposedly
Another thing that would be cool, is to find a agency commercial gun store or something like that. In short, not the "commercial" for the civilian market since the guns would have burst/full auto, meant for military and police. But the guns there arent adapted officially yet. I can't explain it better than that, i found out about this while reading about the 723 and how it's history and lore is with its adaptation. But, if it is like an office or something you can enter that this "commercial market" is, that would be sick to add such buildings to the world to find. But again, i dont know more than that its all speculation and assumption basically.
I just know that the M4, the official one is what was officially adopted by the military. While everything else, all the prototypes that eventually made the M4 were "self bought" or something like that. And delta force apparently did that with the colt 723.
Source: https://www.youtube.com/watch?v=cMFH0ZgFIHE