I've been using Opera for quite a long time, since the 11 series, and I've had quite a couple of issues with Opera over the years, but the issue that came up from the auto-update from Opera 26 to 27 makes the browser damn near unusable.
My current problem is as follows: While trying to browse using Opera 27, everything in the browser is slowed, as in slow to load, slow to respond to my clicks, slow to everything in general. Furthermore, anytime I attempt to watch a video on say Youtube or even look at an image, the browser either chugs or gets stuck in an endless cycle of loading where either one of two things happens, either the browser becomes unresponsive and needs to be restarted or the browser goes into a "Not Responding" phase with every action I take. All delays that occur, even typing here, are four seconds in delay (yes, I timed it.) To test, I used Firefox and Chrome, using the same websites and videos with zero issues. Flash and the like are all up to date. I hope this gets patched in 28 otherwise I wont be able to use Opera because this right here makes no sense.
This is my version info:
Version: 27.0.1689.69 - Opera is up to date
Update stream: Stable
System: Windows 8.1 64-bit (WoW64)