When I rebuild the index I wait about 15 minutes. Although when I connect to w3wp in debug mode, I see that GetAllData work out for about 7 seconds.

Why build indexes takes so long? Is it possible to speed up?

I add in my ExamineIndex.config:

  <IndexSet SetName="OrganizationsIndexSet" IndexPath="~/App_Data/TEMP/ExamineIndexes/OrganizationsIndexSet/" >
    <IndexUserFields>
      <add Name="Id"/>
      <add Name="Url"/>
      <add Name="Category"/>
    </IndexUserFields>
  </IndexSet>

ExamineSettings.config:

    <Examine>
      <ExamineIndexProviders>
        <providers>
          <add name="InternalIndexer" type="UmbracoExamine.UmbracoContentIndexer, UmbracoExamine"
               supportUnpublished="true"
               supportProtected="true"
               analyzer="Lucene.Net.Analysis.WhitespaceAnalyzer, Lucene.Net"/>

          <add name="InternalMemberIndexer" type="UmbracoExamine.UmbracoMemberIndexer, UmbracoExamine"
               supportUnpublished="true"
               supportProtected="true"
               analyzer="Lucene.Net.Analysis.Standard.StandardAnalyzer, Lucene.Net"/>   

            <add name="ExternalIndexer" type="UmbracoExamine.UmbracoContentIndexer, UmbracoExamine"/>                   

          <add name="OrganizationsIndexer"
               type="Examine.LuceneEngine.Providers.SimpleDataIndexer, Examine"
               dataService="Podoroznik.OrganizationsDataService, Podoroznik"
               indexSet="OrganizationsIndexSet" 
               analyzer="Lucene.Net.Analysis.Standard.StandardAnalyzer, Lucene.Net"
               indexTypes="CustomData"
               runAsync="false"/>
        </providers>
      </ExamineIndexProviders>

      <ExamineSearchProviders defaultProvider="ExternalSearcher">
        <providers>
          <add name="InternalSearcher" type="UmbracoExamine.UmbracoExamineSearcher, UmbracoExamine"
               analyzer="Lucene.Net.Analysis.WhitespaceAnalyzer, Lucene.Net"/>

          <add name="ExternalSearcher" type="UmbracoExamine.UmbracoExamineSearcher, UmbracoExamine" />

          <add name="InternalMemberSearcher" type="UmbracoExamine.UmbracoExamineSearcher, UmbracoExamine"
               analyzer="Lucene.Net.Analysis.Standard.StandardAnalyzer, Lucene.Net" enableLeadingWildcard="true"/>

          <add name="OrganizationsSearcher" type="UmbracoExamine.UmbracoExamineSearcher, UmbracoExamine" analyzer="Lucene.Net.Analysis.Standard.StandardAnalyzer, Lucene.Net"/>
        </providers>
      </ExamineSearchProviders>

    </Examine>

And my OrganizationsDataService.cs:

using System.Collections.Generic;
using System.Linq;
using Examine;
using Examine.LuceneEngine;
using Umbraco.Core.Models;
using Umbraco.Web;

namespace Podoroznik
{

    public class OrganizationsDataService : ISimpleDataService

    {
        public IEnumerable<SimpleDataSet> GetAllData(string indexType)

        {
            var helper = new UmbracoHelper(UmbracoContext.Current);
            var data = new List<SimpleDataSet>();

            foreach (var content in helper.TypedContent(1127).Descendants("Organization").Where("Visible"))
            {
                Organization organization = new Organization() { Id = content.Id, Url = content.Url };
                IPublishedContent categoriesNode = content.Children.FirstOrDefault(z => z.DocumentTypeAlias == "categoriesNode");

                if (categoriesNode != null)
                {
                    foreach (var x in categoriesNode.Children())
                    {
                        organization.Category = x.GetPropertyValue<string>("category");
                        AddOrganization(data, organization);
                    }
                }
                else
                {
                    AddOrganization(data, organization);
                }

            }
            return data;
        }
        public class Organization
        {
            public int Id { get; set; }
            public string Url { get; set; }
            public string Category { get; set; }
        }

        private void AddOrganization(List<SimpleDataSet> data, Organization item)
        {
            data.Add(new SimpleDataSet()
            {
                NodeDefinition = new IndexedNode()
                {
                    NodeId = item.Id, Type = "CustomData"
                },

                RowData = new Dictionary<string, string>()
                    {
                        {"id", item.Id.ToString()},
                        {"url", item.Url},
                        {"category", item.Category}
                    }
            });
        }
    }
}

Umbraco 7.2.6