A couple of days before 1.14 was implemented onto the server, me and madlifer were building an chest room item sorter.
Now the change we noticed when 1.14 was implemented, is that hoppers no longer work as they were in 1.13.
For example the hopper used to take 3 blocks/items second and now it takes 1 item per hopper tick which is the minecraft Default setting,
we noticed that because in order to make an item sorter you need to have 41 items/blocks and 4 names blocks/items in a hopper which is powered by a comperator and redstone torch. In 1.13 for example if we put 1 cobblestone in the Input chest it would go through the hoppers and take 2 more cobblestone that are in the sorter hopper, from 41 cobblestone to 39, it took the 2 from the hopper and the one we put in.
Which brings us in 1.14 where hoppers work differently, that is maybe causing the lag.