Following Tom's suggestion that we split out individual issues with 2.1 into separate posts, I'll provide my observations on a possible memory leak here. I've also posted details on the LM forum.
We all know that OOMs can be triggered by a combination of complex airplanes and airport sceneries. However what I'm seeing happens when flying over the treescapes of northern Canada. With any setting of the vegetation autogen slider greater than 'none', and at a height where vegetation is visible, I can watch the free VAS counter gradually decrement, eventually leading to an OOM. When I set the slider to 'none', the free VAS remains static. My conclusion is that there is some sort of memory leak when there is visible vegetation autogen.
I've also tested this, in exactly the same conditions, with version 2.0, and free VAS remains rock solid constant, and so it does seem to be a problem unique to 2.1. I'm using FTX Global vegetation, but another poster in this forum reported the same problem with default vegetation, so the vegetation type does not seem to be a factor. Neither is the setting for buildings, it's just a problem with vegetation.
It's a shame, because for me 2.1 is better in most other respects. Unfortunately, in the software world, it can often be 'ten steps forward, one step back'.