Also I'm aware that the only security patch that Opera 12.17 has received in a long time was the Heartbleed patch. For that reason I always run it under StripMyRights and it modifies the security token so that if any malware is encountered via the browser it only gets limited user rights instead of system wide priviledges - I use an account with admin rights. They say that malware usually obtains the same rights as the current user.
Why not simply run the critical program as a different user account? You can use the "run as another user" option to launch it (or build a proper shortcut) and the browser gets completely isolated from both admin rights and your entire user profile where your private data lies typically. The nice part is that this doesn't require any third party crapware, it's all using the capabilities built in into the OS!
Also applies to most other operating systems too. Actually this is what Android does under the hood