diff --git a/changelogs/unreleased/16117-improve-search-for-issues.yml b/changelogs/unreleased/16117-improve-search-for-issues.yml
new file mode 100644
index 00000000000..92d5820ddd2
--- /dev/null
+++ b/changelogs/unreleased/16117-improve-search-for-issues.yml
@@ -0,0 +1,5 @@
+---
+title: Improve search query for issues.
+merge_request:
+author:
+type: performance
diff --git a/lib/gitlab/search_results.rb b/lib/gitlab/search_results.rb
index 7037e2e61cc..ca48c6df602 100644
--- a/lib/gitlab/search_results.rb
+++ b/lib/gitlab/search_results.rb
@@ -82,7 +82,10 @@ module Gitlab
     end
 
     def issues
-      issues = IssuesFinder.new(current_user).execute.where(project_id: project_ids_relation)
+      issues = IssuesFinder.new(current_user).execute
+      unless default_project_filter
+        issues = issues.where(project_id: project_ids_relation)
+      end
 
       issues =
         if query =~ /#(\d+)\z/
diff --git a/spec/lib/gitlab/search_results_spec.rb b/spec/lib/gitlab/search_results_spec.rb
index a958baab44f..edd3d74f344 100644
--- a/spec/lib/gitlab/search_results_spec.rb
+++ b/spec/lib/gitlab/search_results_spec.rb
@@ -52,15 +52,36 @@ describe Gitlab::SearchResults do
       expect(results.objects('merge_requests')).to include merge_request_2
     end
 
-    it 'includes project filter by default' do
-      expect(results).to receive(:project_ids_relation).and_call_original
-      results.objects('merge_requests')
+    describe '#merge_requests' do
+      it 'includes project filter by default' do
+        expect(results).to receive(:project_ids_relation).and_call_original
+
+        results.objects('merge_requests')
+      end
+
+      it 'it skips project filter if default project context is used' do
+        allow(results).to receive(:default_project_filter).and_return(true)
+
+        expect(results).not_to receive(:project_ids_relation)
+
+        results.objects('merge_requests')
+      end
     end
 
-    it 'it skips project filter if default is used' do
-      allow(results).to receive(:default_project_filter).and_return(true)
-      expect(results).not_to receive(:project_ids_relation)
-      results.objects('merge_requests')
+    describe '#issues' do
+      it 'includes project filter by default' do
+        expect(results).to receive(:project_ids_relation).and_call_original
+
+        results.objects('issues')
+      end
+
+      it 'it skips project filter if default project context is used' do
+        allow(results).to receive(:default_project_filter).and_return(true)
+
+        expect(results).not_to receive(:project_ids_relation)
+
+        results.objects('issues')
+      end
     end
   end