Right now we have had a lot of bugs reported over the holidays and one of our team has been adding them to our internal bug tracking.
That bug tracer still has some spare memory to add anything new?
2/ Game freezes if i enter diplomatic screen during Ai turn.
Don't enter diplomatic screen during AI turn then, It should be locked out anyway with many other things.
I prefer not to do anything at all, and at the start of new turn wait a sec or two, things go smother this way at galaxy size I play.
1/ Not getting legions back when decommisioning transports. (If a bug and not a change.)
This is little illogical but was never a problem for me, I prefer to upgrade ships, its not that expansive for cargo hull and I don't have to waste entire turn of shipyard time to build new one.