Many thanks for your advice. I currently deactivate streaming before changing any SDR parameters, then re-activate after. With 2 channels enabled the activation and deactivation takes a little while. I will try the latest LimeSuite build, as recommended in your reply to my previous post https://discourse.myriadrf.org/t/lime-sdr-slowness-with-2-channels-enabled/5284/2, but failing this I will try leaving streams activated and flush sample stream.
Thanks again for your help.