Hello @Egbejiogu,
Thank You for posting your query onto the Forum.
When it comes to report optimization this has always been a debatable topic because for some people a particular report may be quick enough whereas for others it may still be considered as a slow report. Since the topic is very much subjective the answers will tend to differ from people to people about the ranges that may specify.
I’m providing a link below where a specific post was created just to address this type of issue. I contains good amount of videos, articles and a discussion from some of our experts about how to address this issue and optimize the report.
I’m also providing few links below of some of the blog posts as well as of the documentation from the Microsoft based on this topic.
Hoping you find this useful and helps you in optimizing the reports. 
Thanks and Warm Regards,
Harsh
https://maqsoftware.com/expertise/powerbi/power-bi-best-practices
