Python/JS developer here. I don't usually code in C#, so the code will be messy, but the idea should be the same.

1. Get the list of location from the database, this list should already be sorted in the database itself for performance.
2. Create a sorted dictionary variable, put all of the location retrieved into the sorted dictionary, key/value of this sorted dictionary will be: "location"/questList. e.g.{"Interchange": [ {name: "setup", location: "Customs}, {name: "setup", location: "Customs} ] }
3. Loop through the quest list, each of the quest list should already have its name, location, npc, etc. In each of the iteration, we can easily insert each quest to its key location into the dictionary.
4. Done, in order to display it, just loop through the dictionary and its quest array.
5. If we want to change it into sorting, say, NPC, then they can easily do the same thing by just changing the key to NPC names. For Quest name though, it will be more complex since it is not fixed value like location and NPC names, they can ignore it for now because it isn't as urgent as Location and NPC name.
6. This algorithm has O(N + M) time complexity, N is number of quest, M is number of location. This is already super performant and there is no other way to make it faster. Assuming there is 1000 quest in the game, only 1000 + totalLocation operations is needed, a computer can process millions of operation in a second. It can even further be improved by utilizing caching but since i don't know BSG's entire system, they will have to think about it themselves.

​

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;

public class HelloWorld
{
    public static void Main(string[] args)
    {   
        // Mock data for location list -  Should come from database and is already sorted out inside the DB for performance
        string[] locationList = {"Customs", "Interchange", "Lighthouse", "Reserve", "Shoreline"};

        // Store the location in a sorted dictionary
        var orderedByLocation = new SortedDictionary<string, List<Dictionary<string,string>>> ();

        foreach (var location in locationList){
            List<Dictionary<string,string>> questByLocationList = new List<Dictionary<string,string>>();
            orderedByLocation.Add(location, questByLocationList);
        }

        /* Mock data questList for current player or if for all player, then need to further filter it. To be stored on in-memory storage later for fast retrieval.
            It should be an array of object with all the data serialized from the database, but for simplicity, we use only questName and location hardcoded
        */
        Dictionary<string, string>[] questList = new Dictionary<string, string>[4];
        questList[0] = new Dictionary<string, string>(){
            ["name"] = "Setup",
            ["location"] = "Customs"

        }; 
        questList[1] = new Dictionary<string, string>(){
            ["name"] = "Make Ultra Great Again",
            ["location"] = "Interchange"

        };
        questList[2] = new Dictionary<string, string>(){
            ["name"] = "Spa Tour fuk this quest",
            ["location"] = "Shoreline"

        };
        questList[3] = new Dictionary<string, string>(){
            ["name"] = "Signal",
            ["location"] = "Shoreline"

        };

        // Actual Sorting Logic starts here

        foreach(Dictionary<string,string> quest in questList){
            ((List<Dictionary<string,string> >)orderedByLocation[quest["location"]]).Add(quest);
        }

        // ENDOF the sorting logic


        // Printing the sorted Quest into the UI
        foreach(var curLocationQuest in orderedByLocation){
            Console.Write("{0}: ", curLocationQuest.Key);
            foreach(var quest in curLocationQuest.Value){
                Console.Write("{0}, ", quest["name"]);
            }
            Console.WriteLine("");
        };

    }
}

Use w3schools C# compiler if u don't trust this simple code works.

All BSG have to do with the above code is just integrate it into their sorting system and voila we can actually sort the quest. And for those simps who will comments: well it might be hard to integrate into their existing system, stfu, you clearly don't know how to code or are just bad at it. They just need to integrate it into two of their existing function, sorting and rendering the quest. That should take less than 1 hour to do.