Is it possible, at this point, to spread a render across multiple sessions? This would be a great help to those of us who are running slower machines.
For this to work, you'd need to use render tiling, but this feature isn't implemented in TG2. Hopefully it will be in the future.
In the meantime, you can do crop renders, and then reassemble the pieces in a 2D app like photoshop. Just make sure GI is turned off, or it will add a slight haze effect to the edges of each rendered crop. I am hoping they fix this issue in future updates.
I wish they would do smaller incremental updates, rather than larger ones, so we'd slowly gain more features in TG2.
If you want, you can use the pause/resume render button to pause a render and free up your CPU. Your RAM will still be used, so depending on your problem, that might not help. As for the updates, I understand why you might get impatient, but something as complex as TG2 takes a long time to develop, and things need to be tested so that they are relatively stable when they are released to the general public.
Apart from competing for the CPU if you only have a single (non dual core) processor, the biggest limiting factor will probably be RAM usage. If performing one render uses nearly all of your RAM there is no way you will be able to do two simultaneous renders.