jenkins deployment making the build very slow

Question

I am new to Jenkins. I am doing a build through Jenkins, but the build is very slow. Is there any way I can speed it up?

#!/usr/bin/env groovy
@Library('cplib') _

import com.sports.paas.cplib.helpers.Build
import com.sports.paas.cplib.helpers.Workspace
import com.sports.paas.cplib.utils.Openshift

def bld = new Build()
def wspace = new Workspace()   
def osh = new Openshift()
def appReleaseTag = ""

def NODE_HOME = "${JENKINS_HOME_SLAVE}/tools/jenkins.plugins.nodejs.tools.NodeJSInstallation/Node_6.11.1"
def projectName = "player"
def appName = "ball"
def appOcpConfigBranch = "master"


// ########################################################################################
// PIPELINE WORKFLOW
// ########################################################################################
pipeline {

    agent { node('nodejs')}
    tools {
        nodejs 'nodejs-8.11.2'
    }

    options {
        disableConcurrentBuilds()
        buildDiscarder(logRotator(numToKeepStr: '30', daysToKeepStr: '15'))
        skipDefaultCheckout(true)
        timestamps()
        skipStagesAfterUnstable()
    }

    parameters {
        choice (
            name : 'DEPLOY_ENVIRONMENT',
            choices: ' \nunit\ntest\nstage',
            description: '[Required] Select the location to deploy.'
        )
    }


    stages {

        stage('Prepare') {
            steps {
                script {
                    log.info "Explicit scm checkout ..."
                    checkout scm
                    wspace.init()
                // wspace.checkoutAppOcpConfig(appName, appOcpConfigBranch)
                    appReleaseTag = wspace.getBuildProperty("version") + "." + env.BUILD_NUMBER
                }
            }
        }

        stage('Build Artifacts') {
            steps {
                script {
                    sh """
                        echo "Building artifacts ..."
                        export PATH=$PATH:$NODE_HOME/bin;
                        echo "Running node build ..."
                        # Please build your application using npm or yarn. Application build 
                        #       using yarn has been tested for a 35% faster execution when compared to yarn.
                        #npm install --no-optional --production --silent
                        npm install

                        echo "@@@ NPM RUN PROD ( BUILD )"
                        npm run build
                        #yarn
                    """
                }
                prepareForBuildImage()
            }
        }

        stage('Build Image') {
            steps {
                script {
                    if(!wspace.releaseVersionExists()) {
                        appReleaseTag = osh.buildAppImage(appName, appReleaseTag)
                    } else {
                        appReleaseTag = env.RELEASE_VERSION
                    }                        
                }
            }
        }

        stage('Deploy Unit') {
            steps {
                script {
                    envName=env.DEPLOY_ENVIRONMENT
                    osh.deploy(projectName+"-"+envName, appName, envName,appReleaseTag)
                }
            }
        }

    } //stages
} // pipeline

def prepareForBuildImage() {
    sh '''
        echo "Preparing Image contents ..."
        rm -rf tmp
        mkdir -p tmp
        chmod -R 777 tmp
        echo "Compressing files ..."
        tar cvzf tmp.tar.gz client server *.json node_modules index.js build.properties README.md
        cp -pr tmp.tar.gz tmp/ 
        echo "Decompressing files ..."
        cd tmp
        tar xvzf tmp.tar.gz
        rm -fr tmp.tar.gz
        cd ..
        echo "Displaying deployment artifacts ..."
        ls -Rlt tmp/ --ignore=node_modules
    '''
}