makedit - if you are trying to maximise performance, you should enable WebGL. It's over twice as fast in Chrome and Firefox. Why have you disabled it?
It is very difficult for us to do anything about your performance issue unless you share a .capx which runs fast in r84 and slow in r100. We generally make small performance improvements in updates, so it would be unusual if it is suddenly a lot slower. I can't see anything in the r85 changelog that indicates any serious changes were made regarding performance either, so I wouldn't know where to start without your .capx.
Opera 12 still does not have hardware acceleration on by default nor WebGL support, so it is very difficult to get good framerates with it. If you are interested in optimising for software rendering, try enabling 'Pixel rounding' in project properties and setting 'Sampling' to 'Point', which can help a little. Generally we optimise for Firefox and Chrome since these browsers have high quality hardware acceleration and the largest market share. IE does not support WebGL but still performs relatively well in our benchmarks - far better than Safari and Opera, at least. We are highly focused on making a stable and high performance engine, but a lot of the work depends on the browser makers, and in my opinion Opera and Safari are falling behind other browsers in this regard.