V8 5.2 appears to be 3x slower than V8 3.27 when running for loops

[Jeff Hoefs]

We have a UI prototyping tool for Android that uses V8 under the hood. Recently we upgraded from V8 3.27.34.4 to V8 5.2 (so we could get es2015 support) but now the frame rate when dragging a single object on the screen has dropped from 60 fps to 20 fps (running the exact same JavaScript code). The JavaScript code that is being executed is in a touch handler that runs through several nested for loops. This ran smooth in V8 3.27 (but we obviously want to move on so we can use es2015). Does V8 5.2 have any known performance issues (especially in executing for loops)? Perhaps upgrading to a newer version will resolve the issue?

[Jeff Hoefs]

I should add... this performance drop is only seen when running on an Android Wear watch (1.1 Ghz, clocked down to even further). On a phone or desktop you'll see 60 fps in both V8 5.2 and 3.27, it's only when you drop into the sub 1Ghz range that you see the steep drop in V8 5.2 (3.27 still gets 60 fps even on the watch).