diff --git a/cmake/common/clang-tidy.config b/cmake/common/clang-tidy.config
index 9be7d5830..c69b9009c 100644
--- a/cmake/common/clang-tidy.config
+++ b/cmake/common/clang-tidy.config
@@ -1,5 +1,5 @@
 {
-  "Checks": "-*, concurrency-*, modernize-*, portability-*",
+  "Checks": "-*, concurrency-*, modernize-*, performance-*, portability-*",
   "WarningsAsErrors": "*",
   "FormatStyle": "none",
   "UseColor": true
diff --git a/src/core/json/include/sourcemeta/core/json_value.h b/src/core/json/include/sourcemeta/core/json_value.h
index 6169a004a..10c8ee6a1 100644
--- a/src/core/json/include/sourcemeta/core/json_value.h
+++ b/src/core/json/include/sourcemeta/core/json_value.h
@@ -45,7 +45,7 @@ class SOURCEMETA_CORE_JSON_EXPORT JSON {
   /// The object type used by the JSON document.
   using Object = JSONObject<String, JSON, PropertyHashJSON<JSON::String>>;
   /// The parsing phase of a JSON document.
-  enum class ParsePhase { Pre, Post };
+  enum class ParsePhase : std::uint8_t { Pre, Post };
   // The enumeration indexes must stay in sync with the internal variant
   /// The different types of a JSON instance.
   enum class Type : std::uint8_t {
diff --git a/src/core/jsonpointer/include/sourcemeta/core/jsonpointer_template.h b/src/core/jsonpointer/include/sourcemeta/core/jsonpointer_template.h
index 0a6eb600f..80be97a02 100644
--- a/src/core/jsonpointer/include/sourcemeta/core/jsonpointer_template.h
+++ b/src/core/jsonpointer/include/sourcemeta/core/jsonpointer_template.h
@@ -5,6 +5,7 @@
 
 #include <algorithm>        // std::copy, std::all_of
 #include <cassert>          // assert
+#include <cstdint>          // std::uint8_t
 #include <initializer_list> // std::initializer_list
 #include <iterator>         // std::back_inserter
 #include <optional>         // std::optional, std::nullopt
@@ -16,7 +17,7 @@ namespace sourcemeta::core {
 /// @ingroup jsonpointer
 template <typename PointerT> class GenericPointerTemplate {
 public:
-  enum class Wildcard { Property, Item, Key };
+  enum class Wildcard : std::uint8_t { Property, Item, Key };
   struct Condition {
     auto operator==(const Condition &) const noexcept -> bool = default;
     auto operator<(const Condition &) const noexcept -> bool { return false; }
diff --git a/src/core/jsonschema/include/sourcemeta/core/jsonschema_frame.h b/src/core/jsonschema/include/sourcemeta/core/jsonschema_frame.h
index 6cce06386..543f92802 100644
--- a/src/core/jsonschema/include/sourcemeta/core/jsonschema_frame.h
+++ b/src/core/jsonschema/include/sourcemeta/core/jsonschema_frame.h
@@ -105,7 +105,7 @@ class SOURCEMETA_CORE_JSONSCHEMA_EXPORT SchemaFrame {
 public:
   /// The mode of framing. More extensive analysis can be compute and memory
   /// intensive
-  enum class Mode { Locations, References, Instances };
+  enum class Mode : std::uint8_t { Locations, References, Instances };
 
   SchemaFrame(const Mode mode) : mode_{mode} {}
 
diff --git a/src/core/uri/include/sourcemeta/core/uri_escape.h b/src/core/uri/include/sourcemeta/core/uri_escape.h
index 657dc48cb..b35f9eb27 100644
--- a/src/core/uri/include/sourcemeta/core/uri_escape.h
+++ b/src/core/uri/include/sourcemeta/core/uri_escape.h
@@ -5,13 +5,14 @@
 #include <sourcemeta/core/uri_export.h>
 #endif
 
+#include <cstdint> // std::uint8_t
 #include <istream> // std::istream
 #include <ostream> // std::ostream
 
 namespace sourcemeta::core {
 
 /// @ingroup uri
-enum class URIEscapeMode {
+enum class URIEscapeMode : std::uint8_t {
   // Escape every characted that is not in the URI "unreserved" ABNF category
   // See https://www.rfc-editor.org/rfc/rfc3986#appendix-A
   SkipUnreserved,
diff --git a/src/extension/alterschema/include/sourcemeta/core/alterschema.h b/src/extension/alterschema/include/sourcemeta/core/alterschema.h
index b172f76a8..07fb2a706 100644
--- a/src/extension/alterschema/include/sourcemeta/core/alterschema.h
+++ b/src/extension/alterschema/include/sourcemeta/core/alterschema.h
@@ -16,11 +16,13 @@
 
 #include <sourcemeta/core/jsonschema.h>
 
+#include <cstdint> // std::uint8_t
+
 namespace sourcemeta::core {
 
 /// @ingroup alterschema
 /// The category of a built-in transformation rule
-enum class AlterSchemaMode {
+enum class AlterSchemaMode : std::uint8_t {
   /// Rules that simplify the given schema for both human readability and
   /// performance
   Readability,
diff --git a/src/extension/alterschema/linter/draft_official_dialect_without_empty_fragment.h b/src/extension/alterschema/linter/draft_official_dialect_without_empty_fragment.h
index 8bf46af7a..9df6ad563 100644
--- a/src/extension/alterschema/linter/draft_official_dialect_without_empty_fragment.h
+++ b/src/extension/alterschema/linter/draft_official_dialect_without_empty_fragment.h
@@ -39,6 +39,6 @@ class DraftOfficialDialectWithoutEmptyFragment final
   auto transform(sourcemeta::core::JSON &schema) const -> void override {
     auto schema_value = schema.at("$schema").to_string();
     schema_value += "#";
-    schema.at("$schema").into(sourcemeta::core::JSON{std::move(schema_value)});
+    schema.at("$schema").into(sourcemeta::core::JSON{schema_value});
   }
 };
diff --git a/src/extension/alterschema/linter/modern_official_dialect_with_empty_fragment.h b/src/extension/alterschema/linter/modern_official_dialect_with_empty_fragment.h
index 8188f4985..d4439ffb6 100644
--- a/src/extension/alterschema/linter/modern_official_dialect_with_empty_fragment.h
+++ b/src/extension/alterschema/linter/modern_official_dialect_with_empty_fragment.h
@@ -31,6 +31,6 @@ class ModernOfficialDialectWithEmptyFragment final
   auto transform(sourcemeta::core::JSON &schema) const -> void override {
     auto schema_value = schema.at("$schema").to_string();
     schema_value.pop_back();
-    schema.at("$schema").into(sourcemeta::core::JSON{std::move(schema_value)});
+    schema.at("$schema").into(sourcemeta::core::JSON{schema_value});
   }
 };