196764 2019-04-10 00:20:38 -0700 Date.setDate is too slow in WKWebView 2021-02-01 02:34:16 -0800 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified RESOLVED DUPLICATE 218348 InRadar P2 Normal --- 1 348018533 webkit-unassigned fpizlo keith_miller msaboff saam webkit-bug-importer ysuzuki oldest_to_newest 1525891 0 348018533 2019-04-10 00:20:38 -0700 var sTime = Date.now(); var curTime = new Date(); for (var i = 0; i < 10000; i++) { curTime.setDate(i); } console.log(Date.now() - sTime) The execution time of the above code in different browsers: Wkwebview: 16000ms Safari: 120ms Chrome: 3ms 1526781 1 webkit-bug-importer 2019-04-12 10:13:47 -0700 <rdar://problem/49854826> 1724165 2 ysuzuki 2021-02-01 02:34:16 -0800 Now, Safari's perf is on per to Chrome. Note: previously, JSC uses localtime_r. But this is super slow. Now we use ICU instead. *** This bug has been marked as a duplicate of bug 218348 ***