Some guidstypes recently moved and will be moved more into per-map mode.
This for example meaning that each map will have own guid counter and in general will affect only specific map/instance copy until unload. Ofc continents still moslty loaded always, but and in continent this also help slowdown guid counters increase.
Not implemented yet move guid generationfor creatures/GOs to per-map mode also let not generate dynamic guids for static instance spawn, that also slow creature/GO guid counter grow.
Possible item guids can be per-player. I not reseach this case but i think this possible and not remember real need in global item guids counting.
Global guid counters still need for : player guids, pet numbers (maybe per player), guild ids, and auction ids (maybe per auctionhouse).