MacPro after wake-up takes ages before Wi-Fi connects? Basically once my MacPro wakes up, the Wi-Fi icon is greyed out and it takes like a minute (which feels pretty long), before it connects to my home Wi-Fi network.

This happened already a few times over the last year. It starts happening without a good reason, and it fixes itself also like that. Utterly annoying.

I cleaned up my Wi-Fi list (only 3 networks in it) and my home network is on the top.

Running 10.13.3

Any clues?
Did you try to delete your wifi settings? 


Go go to System Preferences > Network > Use the (-) to delete wifi. Use the (+) to add a new wifi setting.
Do you use additional network settings e.g. Ethernet or iPhone USB? If so, try to disable them or set the Service Order accordingly.
It could be a network issue. Maybe your wifi DHCP Server is slowing things done.