How to increase Redis performance when 100% CPU? Sharding? Fastest .Net Client?

Question

Due to massive load increases on our website redis is now struggling with peak load because the redis server instance is reaching 100% CPU (on one of eight cores) resulting

Answer 1

We found an issue inside our application. Communication about updated data in our cache to the local memory cache was realized through a redis channel subscription.

Every time local cache was flushed, items expired or items were updated messages got sent to all (35) webservers wich in turn started updating more items, etc, etc.

Disabling the messages for the updated keys improved our situation by 10 fold.

Network bandwidth dropped from 1.2 Gbps to 200Mbps and CPU utilization is 40% at 150% the load we had so far at a moment of extreme calculations and updates.