Hey cqjs2001,
I've been using MCM for 7+ years now. It's always been like this and I have a few ideas why. First off, MCM is connecting via an API (back door tunnel) to the servers of these providers. Because this is free, providers might have restrictions on how fast and how much data can be pulled. To much at once and their firewalls might flag MCM as a bot or other attack. MCM has to be authenticated every times it uses their API with a valid token. Additionally, MCM is not only searching for various shows, it switching to other providers as well, and a whole new set of rules. Here is a link to the TVDB API info
https://api.thetvdb.com/swagger#/Users - says tokens expire after 24 hours, something MCM also has to deal with. My point is this - there is a lot going on behind the scenes and MCM has to make sure they don't fray any relationships or we'll all be screwed.
Think of it this way - if you send 100 emails at once Microsoft will flag you as a spammer - but if you send 20 emails, pause for 90 seconds, then 20 more, pause, then 20 more....everything is OK.
So API's are the easy way. But not every source provides an API. Some sources MCM has to actually scrape the web pages to find the information we want. It looks for information known to be in certain locations of the webpage and grabs that data. IMDB for example. Places like TMDB.com are free, and so is their API.
I always looked at MCM as "coffee" application. Turn it on and just go get a cup of coffee while it works it's magic. Even on a cleanly installed OS, my MCM sits for quite a while at times before it rolls into action again. Just try to time your MCM interaction with something else you need to do.
Hope this helps.