Optimizing WebKit & Safari for Speedometer 3.0

This post discusses the performance optimizations made in WebKit and Safari based on the Speedometer 3.0 benchmark. It covers improvements in tooling support, Megamorphic Inline Cache (IC) and Call IC optimizations in JavaScriptCore, optimization of JSON implementations, adjustment of inlining heuristics, lazy JIT code destruction, opportunistic sweeping and garbage collection, miscellaneous optimizations for realistic use cases, improvements in DOM code, layout and rendering, styling performance, inline layout, SVG layout, IOSurface cache hit rate, reducing wait time for GPU Process, AutoFill code optimization in Safari, adjustments in profile-guided optimizations, and the overall results of these optimizations.