Let's get back to the example above: The first "info" permissions are just some "visual" things, chatcolor determines the color of the player's text when he sends a chat message (0xffffff equals white), "shownametag" determines if the nametag (the player's name above his head) should be visible, and "nametagprefix" specifies a prefix for the nametag.
Now it's getting more interesting: All "commands" permission are generally split into an "allow" and "deny" key. Every command you put into the "allow" list will be allowed for the groupmembers (i.e. the player is able to use it), every command you put into the deny list will be disabled. You can use the wildcard character "*" as a replacement for "all commands".
Note: The permissions are parsed from top to bottom, so the example above makes no sense, since the server would allow the two commands first, but then disable all commands. It would make more sense if you put the "deny" block above the "allow" block in this case (so the server would disable all commands first, but then allow the two commands listed under "allow") 
The next block - the "world" permissions - have the same structure. In this case a member of this group would not be able to break any blocks or destroy any objects or constructions.
The "blueprints" part does not have the typical "allow-deny" structure, it's just "key: value" in this case. In this case, the "use" permission (players can use existing blueprints) would be granted, but they are unable to create new blueprints (i.e. copy buildings on your server).
The same applies to the "customimages" block (in this particular case, setting "enabled" to false just disables this feature).
Finally we're coming to an interesting part: The "items" permissions. Here you're able to disable particular items. You can set the permissions for "crafting" (i.e. the player would no longer be able to craft this item), "pickup" (player is no longer able to pickup this item) and "drop" (player is not able to drop this item). Furthermore the "pickup" and "drop" blocks are splitted into "general" (affecting items in the world, e.g. when an item lays on the ground), "chest" (i.e. player is unable to pickup/drop an item from/into chests) and "body" (same as chests, just referring to dead bodies - for example to prevent players from looting dead bodies).
Unfortunately the lag is caused by the huge amount of lamps, every light has an impact on the performance. There will be some improvements for that, but I can't say for sure if this amount of lamps can be handled "lag free" (on the other hands, that always depends on your computer power). 
(red51)
