Custom items make server laggy

Heyyy,
Yesterday I bumped a thread about the same problem which hasen't been solved, and admin probably decided to close for I don't know what reason.
Basically, I've been making some new stuff for my pserver, and items like Armors and Rings seem to work properly, but whenever I use a new Weapon or Ability my friends tell me they start to lag. (Using it when nobody is near me doesn't do anything wrong - I also lag when my friends use them near myself)
I'm using Fabiano's Source and I don't think the problem comes from my side, since the already created "Neggo" Staff makes us also lag.



Hope you can help me solve it

In fabiano you have to edit the xml in the client as well.