Running `clang-tidy -checks='-*,performance-*,-performance-noexcept-*' ...` on WebCore source files found these unnecessary object copies: Source/WebCore/platform/graphics/avfoundation/objc/ImageDecoderAVFObjC.mm:303:83: warning: the parameter 'pair' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] static ImageDecoderAVFObjCSample* toSample(PresentationOrderSampleMap::value_type pair) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:1533:65: warning: the parameter 'asset' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] void MediaPlayerPrivateAVFoundationObjC::setAsset(RetainPtr<id> asset) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:3056:30: warning: parameter 'seekableRanges' is passed by value and only copied once; consider moving it to avoid unnecessary copies [performance-unnecessary-value-param] m_cachedSeekableRanges = seekableRanges; ^ std::move( ) Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:3064:28: warning: parameter 'loadedRanges' is passed by value and only copied once; consider moving it to avoid unnecessary copies [performance-unnecessary-value-param] m_cachedLoadedRanges = loadedRanges; ^ std::move( ) Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:3126:79: warning: the parameter 'metadata' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] void MediaPlayerPrivateAVFoundationObjC::metadataDidArrive(RetainPtr<NSArray> metadata, const MediaTime& mediaTime) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:3168:77: warning: the parameter 'tracks' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] void MediaPlayerPrivateAVFoundationObjC::tracksDidChange(RetainPtr<NSArray> tracks) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateMediaSourceAVFObjC.mm:304:15: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy] for (auto key : m_sampleBufferAudioRendererMap.keys()) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateMediaSourceAVFObjC.mm:315:15: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy] for (auto key : m_sampleBufferAudioRendererMap.keys()) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateMediaSourceAVFObjC.mm:463:15: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy] for (auto key : m_sampleBufferAudioRendererMap.keys()) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/SourceBufferPrivateAVFObjC.mm:1162:74: warning: the parameter 'time' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] MediaTime SourceBufferPrivateAVFObjC::fastSeekTimeForMediaTime(MediaTime time, MediaTime negativeThreshold, MediaTime positiveThreshold) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/SourceBufferPrivateAVFObjC.mm:1162:90: warning: the parameter 'negativeThreshold' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] MediaTime SourceBufferPrivateAVFObjC::fastSeekTimeForMediaTime(MediaTime time, MediaTime negativeThreshold, MediaTime positiveThreshold) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/SourceBufferPrivateAVFObjC.mm:1162:119: warning: the parameter 'positiveThreshold' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] MediaTime SourceBufferPrivateAVFObjC::fastSeekTimeForMediaTime(MediaTime time, MediaTime negativeThreshold, MediaTime positiveThreshold) ^ const & Source/WebCore/platform/graphics/avfoundation/objc/SourceBufferPrivateAVFObjC.mm:1174:55: warning: the parameter 'time' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param] void SourceBufferPrivateAVFObjC::seekToTime(MediaTime time) ^ const &