Existe algum escopo para melhorar o desempenho do meu código?

Tenho um serviço Salesforce Apex REST (LeadService) que processa leads recebidos no formato JSON. Além disso, estou procurando maneiras de aprimorar o tratamento de erros e tornar o código mais fácil de manter. estrutura geral do código

@RestResource(urlMapping='/api/lead')
global class Service {
@HttpPost
global static string createdata(){
   
    RestResponse res = Restcontext.response;
    String requestBody = RestContext.request.requestBody.toString();
    try {   
        // Deserialize JSON data into a list of LeadDataDeserializer objects
        List<LeadDataDeserializer> externalLeads = (List<LeadDataDeserializer>)
            JSON.deserializeStrict(requestBody, List<LeadDataDeserializer>.class);            
        // Transform LeadDataDeserializer objects into Lead data
        List<Lead> students = new List<Lead>();
        for(LeadDataDeserializer info : externalLeads) {
            Lead t_leads = setLeadFields(info);
            t_leads.company='Test Company';
            students.add(t_leads);
        }
        if(students.isEmpty()){
            res.statusCode=400;
            return 'Empty list';
            
           
        }
        else{
            List<Response> responseretn=new List<Response>();
            Database.UpsertResult[] srList = Database.upsert(students, Lead.External_Id__c, false);
            // Process upsert results if needed
            Integer i=0;
            for(Database.UpsertResult upResult:srList){
                if(upResult.isSuccess()){
                    responseretn.add(new Response(upResult.getId(),true,students[i].MobilePhone));
                }
                else{
                    System.debug(upResult.getErrors());
                    responseretn.add(new Response(upResult.getId(),false,students[i].MobilePhone));
                }
                i+=1;
            }
        
            String jsonReqBody=JSON.serialize(responseretn);
            res.statusCode = 201;
            return jsonReqBody;
            
           
                            
        }
        
    } catch(Exception e) {
        // Handle exceptions
        res.Statuscode = 500;
        return 'Internal Server Error';

        
    }
}
//Response wrapper to return
public class Response{
    public string leadId{get;set;}
    public boolean isSuccess{get;set;}
    public string mobilePhone{get;set;}
    
    public Response(String leadId,Boolean isSuccess,String mobilePhone){
        this.leadId=leadId;
        this.isSuccess=isSuccess;
        this.mobilePhone=mobilePhone;
    }
}

public static Lead setLeadFields(LeadDataDeserializer info){
    Lead extLead=new Lead();
    extLead.LastName=info.Name;
    extLead.CountryCode__c=info.countryCode; 
    extLead.MobilePhone=info.phoneNumber;
    extLead.mx_WhatsApp_Number__c=extLead.MobilePhone;
    extLead.mx_IP_Address__c=info.ipAddress;
    extLead.External_Id__c=extLead.MobilePhone;
    if(info.leadStage!=null){
        extLead.Status=info.leadStage;
    }
    if(info.campaignName!=null){
        extLead.mx_Campaign_Name__c=info.campaignName;
    }
    if(info.campaignSource!=null){
        extLead.SourceCampaign__c=info.campaignSource;
    }

    //20 more if conditions with null check like above (serializeddata.field!=null)
   
    return extLead;
}}

Estou usando várias instruções if para tratar apenas para incluir campos que possuem valor e não para substituir o valor do registro anterior se o valor proveniente da integração estiver vazio

Como isso pode ser tratado de forma eficiente?