Rendering a sample scene [a cube over a plane] with ambient occlusion in the 2.33a release and 8x OSA turned on, takes 17 seconds.
In the new 2.34 release, rendering the exact same scene takes 1 minute, 30 seconds. Those optimizations were nice, even if sometimes leading to very slight artifacts. I wish there was an option to re-enable them for raytracing if so desired.
There is no difference in the final output. With complex scenes, yes, maybe a magnifying glass and a sharp eye can spot some flaws in the optimized OSA. But Such a huge ballooning of rendering time to remove such minor imperfections is very bothersome, as there is no option to turn it off.
The sample scene I used is here (although you could make your own in about 20 seconds) Just render it first under 2.33a and then under 2.34, and you will see the difference immediately.