When planning your Sitecore Azure infrastructure it is important to size all resources adequately. In my experience Redis is often undersized and can cause performance issues.
Emer's Blog
My Sitecore adventures
Installing Sitecore in Azure PaaS is straight forward and easy but what do you do when you run into issues that you are unable to reproduce locally, in dev or qa environments? You'll have to collect some data on Azure Web App and review it. Let's go over few ways to do it.
Azure PaaS vs IaaS considerations when configuring multiple Sitecore Content Management instances.
ARR Affinity should be disabled for your Sitecore ContentDelivery role in Azure App Service.