Matomo Slow or Sluggish Dashboard

If your site gets more than 100,000 pageviews per month, you must, must, must enable core:archive. And you must disable browser based archiving.  This can be done in the config/config.ini.php file.

How long does core:archive take to run
A very large site with 12M hits per day (300M hits per month) can take 8 hours to finish the core:archive. This is with some CPU-intensive options enabled, like uniqueness and segments.  Here is one example of a real site which takes 8 hours:

• They have 100 defined segments
  
• They get ~12M hits a day
  
• The largest segments returns 5M visits for the iOS segment