diff --git a/app/controllers/dashboard_controller.rb b/app/controllers/dashboard_controller.rb
index 6195121b931..f9c31920302 100644
--- a/app/controllers/dashboard_controller.rb
+++ b/app/controllers/dashboard_controller.rb
@@ -24,7 +24,7 @@ class DashboardController < Dashboard::ApplicationController
   def load_events
     projects =
       if params[:filter] == "starred"
-        current_user.viewable_starred_projects
+        ProjectsFinder.new(current_user: current_user, params: { starred: true }).execute
       else
         current_user.authorized_projects
       end
diff --git a/app/finders/projects_finder.rb b/app/finders/projects_finder.rb
index f6d8226bf3f..5bf722d1ec6 100644
--- a/app/finders/projects_finder.rb
+++ b/app/finders/projects_finder.rb
@@ -7,6 +7,7 @@
 #   project_ids_relation: int[] - project ids to use
 #   params:
 #     trending: boolean
+#     owned: boolean
 #     non_public: boolean
 #     starred: boolean
 #     sort: string
@@ -28,13 +29,17 @@ class ProjectsFinder < UnionFinder
 
   def execute
     items = init_collection
-    items = by_ids(items)
+    items = items.map do |item|
+      item = by_ids(item)
+      item = by_personal(item)
+      item = by_starred(item)
+      item = by_trending(item)
+      item = by_visibilty_level(item)
+      item = by_tags(item)
+      item = by_search(item)
+      by_archived(item)
+    end
     items = union(items)
-    items = by_personal(items)
-    items = by_visibilty_level(items)
-    items = by_tags(items)
-    items = by_search(items)
-    items = by_archived(items)
     sort(items)
   end
 
@@ -43,10 +48,8 @@ class ProjectsFinder < UnionFinder
   def init_collection
     projects = []
 
-    if params[:trending].present?
-      projects << Project.trending
-    elsif params[:starred].present? && current_user
-      projects << current_user.viewable_starred_projects
+    if params[:owned].present?
+      projects << current_user.owned_projects if current_user
     else
       projects << current_user.authorized_projects if current_user
       projects << Project.unscoped.public_to_user(current_user) unless params[:non_public].present?
@@ -56,7 +59,7 @@ class ProjectsFinder < UnionFinder
   end
 
   def by_ids(items)
-    project_ids_relation ? items.map { |item| item.where(id: project_ids_relation) } : items
+    project_ids_relation ? items.where(id: project_ids_relation) : items
   end
 
   def union(items)
@@ -67,6 +70,14 @@ class ProjectsFinder < UnionFinder
     (params[:personal].present? && current_user) ? items.personal(current_user) : items
   end
 
+  def by_starred(items)
+    (params[:starred].present? && current_user) ? items.starred_by(current_user) : items
+  end
+
+  def by_trending(items)
+    params[:trending].present? ? items.trending : items
+  end
+
   def by_visibilty_level(items)
     params[:visibility_level].present? ? items.where(visibility_level: params[:visibility_level]) : items
   end
diff --git a/app/models/project.rb b/app/models/project.rb
index a59095cb25c..457399cb60e 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -242,6 +242,7 @@ class Project < ActiveRecord::Base
   scope :in_namespace, ->(namespace_ids) { where(namespace_id: namespace_ids) }
   scope :personal, ->(user) { where(namespace_id: user.namespace_id) }
   scope :joined, ->(user) { where('namespace_id != ?', user.namespace_id) }
+  scope :starred_by, ->(user) { joins(:users_star_projects).where('users_star_projects.user_id': user.id) }
   scope :visible_to_user, ->(user) { where(id: user.authorized_projects.select(:id).reorder(nil)) }
   scope :non_archived, -> { where(archived: false) }
   scope :for_milestones, ->(ids) { joins(:milestones).where('milestones.id' => ids).distinct }
@@ -350,10 +351,6 @@ class Project < ActiveRecord::Base
       where("projects.id IN (#{union.to_sql})")
     end
 
-    def search_by_visibility(level)
-      where(visibility_level: Gitlab::VisibilityLevel.string_options[level])
-    end
-
     def search_by_title(query)
       pattern = "%#{query}%"
       table   = Project.arel_table
diff --git a/app/models/user.rb b/app/models/user.rb
index 3f816a250c2..9aad327b592 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -557,12 +557,6 @@ class User < ActiveRecord::Base
     authorized_projects(Gitlab::Access::REPORTER).where(id: projects)
   end
 
-  def viewable_starred_projects
-    starred_projects.where("projects.visibility_level IN (?) OR projects.id IN (?)",
-                           [Project::PUBLIC, Project::INTERNAL],
-                           authorized_projects.select(:project_id))
-  end
-
   def owned_projects
     @owned_projects ||=
       Project.where('namespace_id IN (?) OR namespace_id = ?',
diff --git a/changelogs/unreleased/tc-improve-project-api-perf.yml b/changelogs/unreleased/tc-improve-project-api-perf.yml
new file mode 100644
index 00000000000..7e88466c058
--- /dev/null
+++ b/changelogs/unreleased/tc-improve-project-api-perf.yml
@@ -0,0 +1,4 @@
+---
+title: Improve performance of ProjectFinder used in /projects API endpoint
+merge_request: 11666
+author:
diff --git a/lib/api/groups.rb b/lib/api/groups.rb
index ee85b777aff..e14a988a153 100644
--- a/lib/api/groups.rb
+++ b/lib/api/groups.rb
@@ -151,8 +151,8 @@ module API
       end
       get ":id/projects" do
         group = find_group!(params[:id])
-        projects = GroupProjectsFinder.new(group: group, current_user: current_user).execute
-        projects = filter_projects(projects)
+        projects = GroupProjectsFinder.new(group: group, current_user: current_user, params: project_finder_params).execute
+        projects = reorder_projects(projects)
         entity = params[:simple] ? Entities::BasicProjectDetails : Entities::Project
         present paginate(projects), with: entity, current_user: current_user
       end
diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 226a7ddd50e..d61450f8258 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -256,31 +256,21 @@ module API
 
     # project helpers
 
-    def filter_projects(projects)
-      if params[:membership]
-        projects = projects.merge(current_user.authorized_projects)
-      end
-
-      if params[:owned]
-        projects = projects.merge(current_user.owned_projects)
-      end
-
-      if params[:starred]
-        projects = projects.merge(current_user.starred_projects)
-      end
-
-      if params[:search].present?
-        projects = projects.search(params[:search])
-      end
-
-      if params[:visibility].present?
-        projects = projects.search_by_visibility(params[:visibility])
-      end
-
-      projects = projects.where(archived: params[:archived])
+    def reorder_projects(projects)
       projects.reorder(params[:order_by] => params[:sort])
     end
 
+    def project_finder_params
+      finder_params = {}
+      finder_params[:owned] = true if params[:owned].present?
+      finder_params[:non_public] = true if params[:membership].present?
+      finder_params[:starred] = true if params[:starred].present?
+      finder_params[:visibility_level] = Gitlab::VisibilityLevel.level_value(params[:visibility]) if params[:visibility]
+      finder_params[:archived] = params[:archived]
+      finder_params[:search] = params[:search] if params[:search]
+      finder_params
+    end
+
     # file helpers
 
     def uploaded_file(field, uploads_path)
diff --git a/lib/api/projects.rb b/lib/api/projects.rb
index a827fb26b98..d00d4fe1737 100644
--- a/lib/api/projects.rb
+++ b/lib/api/projects.rb
@@ -68,20 +68,19 @@ module API
           optional :import_url, type: String, desc: 'URL from which the project is imported'
         end
 
-        def present_projects(projects, options = {})
-          options = options.reverse_merge(
-            with: Entities::Project,
-            current_user: current_user,
-            simple: params[:simple],
-            with_issues_enabled: params[:with_issues_enabled],
-            with_merge_requests_enabled: params[:with_merge_requests_enabled]
-          )
+        def present_projects(options = {})
+          projects = ProjectsFinder.new(current_user: current_user, params: project_finder_params).execute
+          projects = reorder_projects(projects)
+          projects = projects.with_statistics if params[:statistics]
+          projects = projects.with_issues_enabled if params[:with_issues_enabled]
+          projects = projects.with_merge_requests_enabled if params[:with_merge_requests_enabled]
 
-          projects = filter_projects(projects)
-          projects = projects.with_statistics if options[:statistics]
-          projects = projects.with_issues_enabled if options[:with_issues_enabled]
-          projects = projects.with_merge_requests_enabled if options[:with_merge_requests_enabled]
-          options[:with] = Entities::BasicProjectDetails if options[:simple]
+          options = options.reverse_merge(
+            with: current_user ? Entities::ProjectWithAccess : Entities::BasicProjectDetails,
+            statistics: params[:statistics],
+            current_user: current_user
+          )
+          options[:with] = Entities::BasicProjectDetails if params[:simple]
 
           present paginate(projects), options
         end
@@ -95,8 +94,7 @@ module API
         use :statistics_params
       end
       get do
-        entity = current_user ? Entities::ProjectWithAccess : Entities::BasicProjectDetails
-        present_projects ProjectsFinder.new(current_user: current_user).execute, with: entity, statistics: params[:statistics]
+        present_projects
       end
 
       desc 'Create new project' do
diff --git a/lib/api/v3/helpers.rb b/lib/api/v3/helpers.rb
index 0f234d4cdad..d9e76560d03 100644
--- a/lib/api/v3/helpers.rb
+++ b/lib/api/v3/helpers.rb
@@ -14,6 +14,33 @@ module API
         authorize! access_level, merge_request
         merge_request
       end
+
+      # project helpers
+
+      def filter_projects(projects)
+        if params[:membership]
+          projects = projects.merge(current_user.authorized_projects)
+        end
+
+        if params[:owned]
+          projects = projects.merge(current_user.owned_projects)
+        end
+
+        if params[:starred]
+          projects = projects.merge(current_user.starred_projects)
+        end
+
+        if params[:search].present?
+          projects = projects.search(params[:search])
+        end
+
+        if params[:visibility].present?
+          projects = projects.where(visibility_level: Gitlab::VisibilityLevel.level_value(params[:visibility]))
+        end
+
+        projects = projects.where(archived: params[:archived])
+        projects.reorder(params[:order_by] => params[:sort])
+      end
     end
   end
 end
diff --git a/lib/api/v3/projects.rb b/lib/api/v3/projects.rb
index 164612cb8dd..896c00b88e7 100644
--- a/lib/api/v3/projects.rb
+++ b/lib/api/v3/projects.rb
@@ -147,7 +147,7 @@ module API
         get '/starred' do
           authenticate!
 
-          present_projects current_user.viewable_starred_projects
+          present_projects ProjectsFinder.new(current_user: current_user, params: { starred: true }).execute
         end
 
         desc 'Get all projects for admin user' do
diff --git a/spec/finders/projects_finder_spec.rb b/spec/finders/projects_finder_spec.rb
index 148adcffe3b..03d98459e8c 100644
--- a/spec/finders/projects_finder_spec.rb
+++ b/spec/finders/projects_finder_spec.rb
@@ -137,6 +137,13 @@ describe ProjectsFinder do
       it { is_expected.to eq([public_project]) }
     end
 
+    describe 'filter by owned' do
+      let(:params) { { owned: true } }
+      let!(:owned_project) { create(:empty_project, :private, namespace: current_user.namespace) }
+
+      it { is_expected.to eq([owned_project]) }
+    end
+
     describe 'filter by non_public' do
       let(:params) { { non_public: true } }
       before do
@@ -146,13 +153,19 @@ describe ProjectsFinder do
       it { is_expected.to eq([private_project]) }
     end
 
-    describe 'filter by viewable_starred_projects' do
+    describe 'filter by starred' do
       let(:params) { { starred: true } }
       before do
         current_user.toggle_star(public_project)
       end
 
       it { is_expected.to eq([public_project]) }
+
+      it 'returns only projects the user has access to' do
+        current_user.toggle_star(private_project)
+
+        is_expected.to eq([public_project])
+      end
     end
 
     describe 'sorting' do
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 2ef3d5654d5..da1b29a2bda 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -948,6 +948,20 @@ describe Project, models: true do
     end
   end
 
+  describe '.starred_by' do
+    it 'returns only projects starred by the given user' do
+      user1 = create(:user)
+      user2 = create(:user)
+      project1 = create(:empty_project)
+      project2 = create(:empty_project)
+      create(:empty_project)
+      user1.toggle_star(project1)
+      user2.toggle_star(project2)
+
+      expect(Project.starred_by(user1)).to contain_exactly(project1)
+    end
+  end
+
   describe '.visible_to_user' do
     let!(:project) { create(:empty_project, :private) }
     let!(:user)    { create(:user) }
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 9edf34b05ad..fe9df3360ff 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -1496,25 +1496,6 @@ describe User, models: true do
     end
   end
 
-  describe '#viewable_starred_projects' do
-    let(:user) { create(:user) }
-    let(:public_project) { create(:empty_project, :public) }
-    let(:private_project) { create(:empty_project, :private) }
-    let(:private_viewable_project) { create(:empty_project, :private) }
-
-    before do
-      private_viewable_project.team << [user, Gitlab::Access::MASTER]
-
-      [public_project, private_project, private_viewable_project].each do |project|
-        user.toggle_star(project)
-      end
-    end
-
-    it 'returns only starred projects the user can view' do
-      expect(user.viewable_starred_projects).not_to include(private_project)
-    end
-  end
-
   describe '#projects_with_reporter_access_limited_to' do
     let(:project1) { create(:empty_project) }
     let(:project2) { create(:empty_project) }