Using tooling from bug 186698, loading can and running "notifyutil -p com.apple.WebKit.dumpHashTableCapacity" shows: Wasted capacity: 101856 bytes (used 29216 of 131072 bytes, utilization: 22.29%) - 1 allocations 1 0x10749b465 WTF::HashTable<WebCore::CSSPrimitiveValue const*, WTF::KeyValuePair<WebCore::CSSPrimitiveValue const*, WTF::String>, WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WebCore::CSSPrimitiveValue const*, WTF::String> >, WTF::PtrHash<WebCore::CSSPrimitiveValue const*>, WTF::HashMap<WebCore::CSSPrimitiveValue const*, WTF::String, WTF::PtrHash<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WTF::String> >::KeyValuePairTraits, WTF::HashTraits<WebCore::CSSPrimitiveValue const*> >::HashTable() 2 0x10749b445 WTF::HashMap<WebCore::CSSPrimitiveValue const*, WTF::String, WTF::PtrHash<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WTF::String> >::HashMap() 3 0x10749b3f5 WTF::HashMap<WebCore::CSSPrimitiveValue const*, WTF::String, WTF::PtrHash<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WTF::String> >::HashMap() 4 0x10749b380 WTF::NeverDestroyed<WTF::HashMap<WebCore::CSSPrimitiveValue const*, WTF::String, WTF::PtrHash<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WTF::String> > >::NeverDestroyed<>() 5 0x10749b325 WTF::NeverDestroyed<WTF::HashMap<WebCore::CSSPrimitiveValue const*, WTF::String, WTF::PtrHash<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WebCore::CSSPrimitiveValue const*>, WTF::HashTraits<WTF::String> > >::NeverDestroyed<>() 6 0x107494a7d WebCore::cssTextCache() 7 0x107496cb7 WebCore::CSSPrimitiveValue::customCSSText() const 8 0x1074c15aa WebCore::CSSValue::cssText() const
<rdar://problem/41189178>