Hello o/ It seems BetterQuesting-3.5.275 is causing a large amount of lag on servers, when more than 1 player is online. Please see the original report for details: EnigmaticaModpacks/Enigmatica2#149
Reverting to 3.5.271 helps a bit, but does not remove the issue.

Forge 1.12.2-14.23.5.2768

I don't know if this is entirely related since I am playing singleplayer, but I am noticing more than 50ms of tps lag. When I check it on lag goggles, it highlighted the script for Better Questing as taking up most of the calculation time (>60ms) which does manifest as some sort of server lag since it is a background script and not a tile entity. I updated the mod from 271 to 276 and noticed the tps lag starting after loading the game on 276, but if I go back to 271 it does not elevate the issue like you are reporting.

For clarity, I believe you were trying to use the word alleviate.

It does sound like you are experiencing the same issue in single player that we were having on our server.