I can confirm that this is a very common occurrence in our private server as well. It is so frequent, we anticipate it and slow down whenever we begin to enter a dense town or city. Once caught up, it seems fine until you leave the area. I believe it may have something to do with loading loot and sturctural details in the environment. It would be ideal to investigate this issue and find a way to optimize loading to reduce or eliminate the lag. Some ideas to consider would be to reduce the proximity of loot that is loaded around a player or delay loading until players leave the vehicle for loot located inside structures (like for items that can't be seen from the vehicle).

It worked! I was able to remove all empty barrels from the truck. Thanks!

In T156838#2164986, @Drift-13b-88 wrote:

Go to rear of truck drag barrel down to normal inventory of truck, walk to side and can then remove from side into hands or on ground. That is only solution I've figured out "if barrel is empty", if barrel has items in it I haven't had any luck or know what to do and barrels get permanently stuck in truck for me, but my friend has been able to get barrels out of truck with loot in them a few times by moving truck.

I have consistently encountered a similar problem with barrels in the Containers collection of the M3S. Items in the Inventory collection can be removed by accessing the side toward the rear corner of the truck. I have yet to find a location to be able to remove any barrels once added. I can't even add items to the barrels once in the truck either.

Relocated the M3S and was now able to remove the barrel that was stuck in the CONTAINERS collection to retrieve the items. However, the inventory for the M3S still shows the barrel collection and its items in the CONTAINERS collection even though the barrel icon is no longer showing a barrel present. Items are not selectable.

I have found this same issue with the trunk for the ADA and the M3S inventory.

The inventory navigation issue seems to be present in other vehicles as well. I have an ADA and the trunk collection does not allow the user to navigate through items. You can only drop the highlighted item out of the trunk to move to the next item. So far, it has not been a problem for non-vehicle containers.