I will add this option in the next patch release which will be out soon.
In the meantime, if you set the polling rate to something long, like 15 or 30 minutes, then it won’t impact your frontend performance much. Keep in mind that this will only affect frontend performance.
If you have issues with the time it takes for your server to respond, then try disabling the exchange rate provider under Wallets -> Rates, or try a different rate provider. That should tell you if the problem comes from that.
There’s also some info in the troubleshooting pages about performance.
Can you describe the performance issue you are facing?
Thanks