Increasing the performance of setting of the class object while iterating throught the resultSet

Question

I am implementing a GET REST API for faster retrieval of records

My Problem : While iterating through the resultSet consisting of 2500-5500 rows , it takes 1 minute 33 seconds to iterate, set the class objects. I want to decrease that time to under 3 seconds

Below given are my sample Table structure consisting of dummy data

ID    A_ID     FIRST_NAME     LAST_NAME    ROLE_NAME

10    jb007      JAMES         BOND           ASSASIN
10    jb007      JAMES         BOND           SHARP-SHOOTER
10    jb007      JAMES         BOND           DOUBLE-AGENT
23    bs312      BOONIE        SMITH          Account Manager
23    bs312      BOONIE        SMITH          Change Manager
21    bb989      BLUNT         BORIS          DEVELOPER
21    bb989      BLUNT         BORIS          MANAGER
21    bb989      BLUNT         BORIS          SERVICE DELIVERY
34    ch201      CHRIS         HUNT           MANGER DEAL LEAD
34    ch201      CHRIS         HUNT           CEO
34    ch201      CHRIS         HUNT           COO
34    ch201      CHRIS         HUNT           MANAGER

As shown above i am having around 2500-5500 rows consisting of data

here is my actual expected response

{
"UserSummary": [{
        "userId": 10,
        "a_id": “jb007”,
        "firstName": “JAMES”,
        "lastName": “BOND”,
        "roles": “ASSASIN,SHARP-SHOOTER,DOUBLE-AGENT”
    }, {
        "userId": 23,
        "a_id": “bs312”,
        "firstName": “BOONIE”,
        "lastName": “SMITH”,
        "roles": “Account Manager,Change Manager”
    },
    {
        "userId": 21,
        "a_id": “bb989”,
        "firstName": “BLUNT”,
        "lastName": “BORIS”,
        "roles": “DEVELOPER,MANAGER,SERVICE DELIVERY”
    },
    {
        "userId": 34,
        "a_id": “ch201”,
        "firstName": “CHRIS”,
        "lastName": “HUNT”,
        "roles": “MANGER DEAL LEAD,CEO,COO,MANAGER”
    }
]

}

Below given is my POJO class

public class UserSummaryResponse {
    private List<UserSummary> userSummary;
    public List<UserSummary> getSequenceUserSummary() {
        return SequenceUserSummary;
    }
    public void setSequenceUserSummary(List<UserSummary> sequenceUserSummary) {
        SequenceUserSummary = sequenceUserSummary;
    }   
}

public class UserSummary {

private Integer userId;
private String a_id;
private String firstName;
private String lastName;
private String Roles;
public Integer getUserId() {
    return userId;
}
public void setUserId(Integer userId) {
    this.userId = userId;
}
public String getA_id() {
    return a_id;
}
public void setA_id(String a_id) {
    this.a_id = a_id;
}
public String getFirstName() {
    return firstName;
}
public void setFirstName(String firstName) {
    this.firstName = firstName;
}
public String getLastName() {
    return lastName;
}
public void setLastName(String lastName) {
    this.lastName = lastName;
}
public String getRoles() {
    return Roles;
}
public void setRoles(String roles) {
    Roles = roles;
}


}

Below given is code logic that i have wrtten to iterate throught resultSet and to set the class Objects

                UserSummaryResponse resp = new UserSummaryResponse();
                List<UserSummary> usLs = new ArrayList<UserSummary>();
                String temp = null;

                rs = ps.executeQuery();
                Integer olduserId = 0;
                temp=null;
                UserSummary usObj = new UserSummary();
                usObj=null;
                while (rs.next()) {
                            int userid = rs.getInt(1);
                            if (userid != olduserId) {
                                if (usObj != null) {
                                    if(temp != null)
                                        usObj.setRoles(temp);
                                usLs.add(usObj);
                                }
                        olduserId = userid;
                        usObj = new UserSummary();
                        usObj.setUserId(rs.getInt(1));
                        usObj.setA_id(rs.getString(2));
                        usObj.setFirstName(rs.getString(3));
                        usObj.setLastName(rs.getString(4));
                        temp = "";
                        }
                        if (temp.length() > 0) {
                            temp += ",";
                            }
                        temp += rs.getString(5);
                        row_count++;
                        }
                        rs.close();
                        if (usObj != null) {
                                    if(temp != null)
                                        usObj.setRoles(temp);
                                usLs.add(usObj);
                                }
                        resp.setSequenceUserSummary(usLs);
                        return resp;

During Unit Testing , i had found that , its taking 1 minute 30-45 seconds to iterate through resultSet and Setting the class objects. Is there any efficient way to increase the setting performance so that it takes less than 3 seconds and thereby increasing the GET API overall performance.