Why has itunes gone really slow again?

When the new version of iTunes came out a few weeks ago, everything was really speedy and support for external storage devices was really good and also very speedy. Since 12.3.0.44 came out, it's gone really sloooooooooow again! It takes ages to complete a backup of my phone and ipad, ages to search for tracks to update with (even though is asks me which library to use before booting up) and ages to populate the apps update page. If I drag and drop a track from my library to a playlist, it judders and jumps all over the place before finally settling on the playlist I want to add it to. In other words, there's a huge amount of lag!

I've just tried updating my phone and it's telling me that "the connection has been reset". I've had this problem a few times before too.

Anybody got any ideas why it's suddenly gone slow with the latest version? Or could Apple look into it and see if anything can be done to speed up the process?

Ta muchly

:-)