Have been in contact with Apple support twice (online chat, in-person appointment at genius bar). Results and advice from support chat: Apple said diagnostics look good, battery condition at 84%, Apple support said fully charged battery important for all day performance, recommended select charge to 100% when put on charger, I asked if I should turn off optimized charging in settings, Apple support said to not turn off optimized charging, recommended taking the watch to apple store for further support. Results from in-person support: diagnostics look good, has this (S4) watch ever been submerged in water (answer is no, it's not exactly water proof), Apple support said it is water resistant and designed for swimming (then why ask?), delete and reinstall apps from Smart Stack (already did that when 10.0 came out), delete third party apps (did that when 10.0 installed), turn off background app refresh (did that when 10.0 installed), reset watch (made no difference). I asked if the software can be reverted back to last OS (9.6.3) because I had none of these problems before watchOS 10. Apple does not support this option (will not is different than cannot). I asked if it would help all-day performance if the battery was replaced? Apple support said yes; however, if the battery has 80% or more capacity the cost is $299, if the battery has less than 80% capacity the cost is $99. Apple said if current performance is not acceptable the watch could be traded in for a credit of $60 toward a new watch, lowest cost equivalent size option with trade-in is about $400 (with tax). Bottom line, watchOS 10 has negatively impacted me, and apparently other users. The only supported solution is a costly forced obsolescence or expensive battery service. Verbal and written feedback has been provided to Apple about the design, performance, and options provided with watchOS 10.