Long pause between turns when finishing tech

Howdy, all...

Could not find this in forum already.

 

Issue: 

Player turn ends.

AI turns process smoothly.

Player turn begins: "Starting new turn".

Game hangs for as long as 10 minutes before play resumes.

 

When it happens: 

Generally after turn 100 or so (though sometimes earlier)

Consistently when player completes research and is loading new tech choices.

Occasionally during non-research-complete turns.

 

It does not happen if a tech is completed mid-turn (inspire scientists, for example).

 

CPU/GPU/memory do not seem to be overly taxed during turn start.

SSD wiped and re-installed.