Run QueryPerformanceTests serialised by default

Tests/AppTests/Helpers/Tag+ext.swift

@@ -0,0 +1,20 @@
+// Copyright Dave Verwer, Sven A. Schmidt, and other contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Testing
+
+
+extension Tag {
+    @Tag static var performance: Self
+}

Tests/AppTests/QueryPerformanceTests.swift

@@ -21,6 +21,8 @@
 
 
 @Suite(
+    .serialized,
+    .tags(.performance),
     .disabled(if: !runQueryPerformanceTests())
 )
 struct QueryPerformanceTests {
@@ -174,7 +176,7 @@
                   JOIN versions v ON v.package_id = p.id
                 WHERE v.reference ->> 'branch' = r.default_branch
                 """)
             try await assertQueryPerformance(query, expectedCost: 132_000, variation: 5000)
         }
     }