[tkone]

v8 used to not be able to optimize blocks containing try/catch, which is why if you needed it, you relegated it to a function containing just the try/catch block.

but since async/await relies on the use of try/catch, last november's (october?) v8 release can optimize try/catch.

plus, it was only ever a v8 issue, not an issue in javascriptcore nor tracemonkey.