Waiting one minute to show material when changing sequence?

In adobe premiere 2017 When changing sequences (since half december) I have to wait about one minute for the material to show.

I installed the newest driver from nvidia and coda is working.  It is 4K material and I made proxies of them. I put the original material to offline. I cleaned the media cache database. So it should fly. Is there anything I can do? Also when trying to call from the netherlands I get a tape the service is not working. I'd love somebody from adobe to log in my system and see what to change. I am editing a documentary at the moment and the director is stressed out.... Hope somebody has tips.

2018 doesn't work for me. But 2017 always used to work.

Warm greetings, Michiel

Hardwareove                                              

My system:

Mac os sierra

MacPro5,1

Processor: 6-Core Intel Xeon

Processorspeed: 3,46 GHz

processors: 2

cores: 12

L2-cache (per core): 256 KB

L3-cache (per processor): 12 MB

memory: 96 GB