Using tooling from bug 186698, loading can and running "notifyutil -p com.apple.WebKit.dumpHashTableCapacity" shows: Wasted capacity: 170920 bytes (used 85720 of 256640 bytes, utilization: 33.40%) - 137 allocations 1 0x10834b3c5 WTF::HashTable<WebCore::WidthCache::SmallStringKey, WTF::KeyValuePair<WebCore::WidthCache::SmallStringKey, float>, WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WebCore::WidthCache::SmallStringKey, float> >, WebCore::WidthCache::SmallStringKeyHash, WTF::HashMap<WebCore::WidthCache::SmallStringKey, float, WebCore::WidthCache::SmallStringKeyHash, WebCore::WidthCache::SmallStringKeyHashTraits, WTF::HashTraits<float> >::KeyValuePairTraits, WebCore::WidthCache::SmallStringKeyHashTraits>::HashTable() 2 0x10834b3a5 WTF::HashMap<WebCore::WidthCache::SmallStringKey, float, WebCore::WidthCache::SmallStringKeyHash, WebCore::WidthCache::SmallStringKeyHashTraits, WTF::HashTraits<float> >::HashMap() 3 0x10834b225 WTF::HashMap<WebCore::WidthCache::SmallStringKey, float, WebCore::WidthCache::SmallStringKeyHash, WebCore::WidthCache::SmallStringKeyHashTraits, WTF::HashTraits<float> >::HashMap() 4 0x10834b1de WebCore::WidthCache::WidthCache() 5 0x10833b065 WebCore::WidthCache::WidthCache() 6 0x10833aee7 WebCore::FontCascadeFonts::FontCascadeFonts(WTF::RefPtr<WebCore::FontSelector, WTF::DumbPtrTraits<WebCore::FontSelector> >&&) 7 0x10833b0cd WebCore::FontCascadeFonts::FontCascadeFonts(WTF::RefPtr<WebCore::FontSelector, WTF::DumbPtrTraits<WebCore::FontSelector> >&&) 8 0x10834378f WebCore::FontCascadeFonts::create(WTF::RefPtr<WebCore::FontSelector, WTF::DumbPtrTraits<WebCore::FontSelector> >&&)
<rdar://problem/41189283>