Hi, @zac everett Welcome to Microsoft Q&A thanks for posting your question.
Latency could be a problem if the cache is on Azure while the website is on prem. However, we have customers who host website on Azure alongside Azure Cache for Redis, but the database is on-prem. So, you can definitely try out some benchmarking, but you might have better success if website is also hosted on Azure.
Please let me know if you have any additional questions.
Regards
Geetha