That's probably one of your best bets.
Also you can turn off javascript, plugins (in general, if you have any) and cookies and increase cache values, latter in case you have enough resources.
Current version of opera would have "plugins on demand" in addition, though I think such exists for 10.10 even if in turbo mode only.
Alternatively you could try elinks or links in text mode.
As for online banking, depends what requirements the specific site would have, e.g. javascript or even ajax capabilities might be required - and not sure which degree of security older browser versions would provide.
Edit: And of course content blocking and perhaps some css which blocks iframes could further reduce traffic.