Some users have found that their Notification Server is taking a long time for console refresh and access. Learn how to speed it up here.
While there are certainly many reasons behind this, one simple reason is documented in a knowledge base article titled:
"How do I Turn off AEX SWD Status Summary Events?"
This KB article gives one option to reduce one area of processing load on the NS. There are some limited reporting tradeoffs here, but for the most part, this is a setting that can easily be adjusted.
See KB 32172 for the full details.