the new app

Most often, delays are caused by network issues, between your controller and router, or the router and the speakers. I’d certainly check the wifi interference FAQ, as well as performing a Sonos network refresh, by unplugging your Sonos devices from power (or powering them off, if battery connected), and rebooting your router. Once the router has recovered, power back on your Sonos devices. This will give them both a fresh IP address, as well as a refresh of the Sonos OS. Finally, check your system for updates, in case there are any that need to be applied.

However, if this behavior continues, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

And how did you convert back to the old app? Android or apple?

I found it when searching the community pages about  the new app problems. Someone had posted a link. I downloaded to my phone and deleted the new app and clicked on the download and it installed. I keep a copy on my phone.  Works well no issues. The danger is the speakers update and make the old app obsolete. I'm going to continue with the old one as I don't experience any issues.