A soon to be dead end.
The biggest improvement was to OOM/VAS. And that only reduces the problem - "Improved memory management reducing overall VAS usage and spikes"
How was that done? By cutting a corner off here or there. Unloading some parts of un-used scenery. Shaving a little one place or another.
In other word, they didn't fix it. They just made it so you can fly a little farther before P3d crashes.
Flying low & slow, OOM's was never a problem for me.
For the high tube flyers who like demanding aircraft like the PMDG planes - again, you can fly a little longer. Before you crash. And burn. And restart Prepar3d again.
What else was improved?
The level of detail range for the ground scenery? No.
For those who don't know, P3d V2.5x has a circle (in the scenery) around the aircraft. Beyond that circle, everything is blurry. I guess that is one of the way that they reduced the OOM/VAS problem. Cutting corners, shaving a little here and there. Yeah, thanks.
Polished metal aircraft skins? Maybe. That's not mentioned per se. Only something about "real-time reflections on objects":
•Cube map render added to system enabling real-time reflections on objects
•Fixed issues with water reflections that were affected by secondary views
•Fixed water rendering issues while using non-tessellated terrain including reflection appearance and shadow brightness
•Fixed bug with fog appearance in reflections
When you get right down to it the "improvements" are very few.
Just look under the title Platform Improvements
How about the very first "improvement"?
"Flights" terminology has been changed to "Scenario" better reflecting Prepar3D's full land, sea, and air training capabilities
All I can say is WOW!

How about:
•Scenario captions now on by default
Double WOW!


And this one:
•Fixed bug where child views could become panel-only after being opened
That one troubled me ALL the time.



And this one too!
•Fixed bug where changing the assignment of the "esc" key would not register
Never again will that be a problem.

Remember, these and other bug fixes are under "Platform Improvements".
I have no doubt that tracking down the huge number of listed bug fixes took a lot of time.
But unless LM pulls a rabbit out of the hat on Wednesday I'm pretty sure that I'm done with Prepar3d.