I did some testing to make sure it wasn't a coincidence. Whenever I play a popular song it instantly starts playing but if it's a more obscure song it takes around 5 seconds to load.
It's a little bit frustrating.
For information: I'm on an Android phone, 1gbps internet plan (i get around 200 mbps on my phone), and my router is set for Cloudflare DNS with Google DNS as back-up.
Did you guys have similar issues?
Source: r/AppleMusic · by /u/heatherr_mason