What’s happening? Out-Of Process Plugins which Mozilla using for Firefox since sometime now without any issues though some users don’t like Firefox plugin_container.exe running in the background and disable it intentionally, Opera seems somehow feels OOPP not right for their browser on Mac platform too.

If you don’t know Opera disabled this technology on 32-bit Windows in Opera 12.02 as a temporary solution to fix the crashes and bring more stability to the browser. OOPS isolates all plugins from browser process and runs in a separate process, (Opera_plugin_wrapper.exe in case of Opera) so that if plugin content crashes then user just needs to reload the page. 

Opera ditches Out of Process Plugins for Mac too

“We have learned from the Opera 12.02 release on Windows that putting plug-ins back into the main process was the right way to go. For Opera 12.10 we have reached the decision to implement the same short-term solution for OS X by putting plug-ins back into the main process” Opera desktop team blog notes.

Opera thinks in-process plugins brings vast improvement in general responsiveness and scrolling performance in heavy sites such as news and popular blogs. And 64-bit distribution still continue to use Out-out of process plugins where 32-bit Mac is affected with this change.

This means 32-bit of Opera 12.10 for Mac and Windows  to ship with in-process plugins.