Hi, having the same problem on my device since OTA 23, I would like to share the following observation: My screen freezes like after every two-three ticks. I have to lock the scree and unlock it and then it will work again for some more ticks before freezing again. So I started uninstalling kind of nearly all the apps (I have the green light to send it to Volla). After uninstalling nearly everything, my Volla worked better. But it did not last for long, because I needed to reinstall some apps for daily use (I use it as my only phone). Now, I see two options: Total reset by Volla or wait for OTA 24. Any other ideas?

@freefrog Thx for answering. I allready switched to google free android since I needed to use my phone. I will try to reinstall Ubuntu on weekend and tell you if it worked.