More aggressively preload on merge request and issue index pages

app/controllers/concerns/issuable_collections.rb

@@ -10,11 +10,11 @@ module IssuableCollections
   private
 
   def issues_collection
-    issues_finder.execute
+    issues_finder.execute.preload(:project, :author, :assignee, :labels, :milestone, project: :namespace)
   end
 
   def merge_requests_collection
-    merge_requests_finder.execute
+    merge_requests_finder.execute.preload(:source_project, :target_project, :author, :assignee, :labels, :milestone, :merge_request_diff, target_project: :namespace)
   end
 
   def issues_finder

app/controllers/concerns/issues_action.rb

@@ -7,7 +7,6 @@ module IssuesAction
 
     @issues = issues_collection
               .non_archived
-              .preload(:author, :project)
               .page(params[:page])
 
     respond_to do |format|

app/controllers/concerns/merge_requests_action.rb

@@ -7,7 +7,6 @@ module MergeRequestsAction
 
     @merge_requests = merge_requests_collection
                       .non_archived
-                      .preload(:author, :target_project)
                       .page(params[:page])
   end
 end

app/controllers/projects/merge_requests_controller.rb

@@ -38,7 +38,6 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   def index
     @merge_requests = merge_requests_collection
     @merge_requests = @merge_requests.page(params[:page])
-    @merge_requests = @merge_requests.preload(:target_project)
 
     if params[:label_name].present?
       labels_params = { project_id: @project.id, title: params[:label_name] }

app/helpers/issuables_helper.rb

@@ -171,9 +171,11 @@ module IssuablesHelper
 
   def issuables_count_for_state(issuable_type, state)
     issuables_finder = public_send("#{issuable_type}_finder")
-    issuables_finder.params[:state] = state
     
-    issuables_finder.execute.page(1).total_count
+    params = issuables_finder.params.merge(state: state)
+    finder = issuables_finder.class.new(issuables_finder.current_user, params)
+
+    finder.execute.page(1).total_count
   end
 
   IRRELEVANT_PARAMS_FOR_CACHE_KEY = %i[utf8 sort page]

app/views/projects/merge_requests/_merge_request.html.haml

@@ -54,15 +54,18 @@
       = link_to namespace_project_commits_path(merge_request.project.namespace, merge_request.project, merge_request.target_branch) do
         = icon('code-fork')
         = merge_request.target_branch
+
     - if merge_request.milestone
        
       = link_to namespace_project_merge_requests_path(merge_request.project.namespace, merge_request.project, milestone_title: merge_request.milestone.title) do
         = icon('clock-o')
         = merge_request.milestone.title
+
     - if merge_request.labels.any?
        
       - merge_request.labels.each do |label|
         = link_to_label(label, subject: merge_request.project, type: :merge_request)
+        
     - if merge_request.tasks?
        
       %span.task-status

changelogs/unreleased/optimize-mr-index.yml

+---
+title: More aggressively preload on merge request and issue index pages
+merge_request: 
+author: