Have only tested in SSP v8.00 and v8.10.
Using 4 Windmills and 5 Solar Collectors was enough to cripple the most powerful computer in my household - a quadcore 3GHz computer. The problem isn't with the memory, however.
Before (MC 1.6.6, IC v7.20), this computer was running with around 250 fps with maximum quality, with 4 Windmills, 5 Solar Collectors, and 4 Watermills. Luckily, I was in the middle of moving stuff around when MC and IC updated, so all my stuff was in my inventory. I set up the 4 Windmills and a 5-Solar Flower, and, when the day came, the fps plummetted to 0. I switched to as little quality as I could, and I still got 0 fps. In fact, I would even bet, despite the fact that MC only shows integer fps, that it would have been .25 or .125 fps. It was really lagging.
And this is while Memory was only around 11% of the default 1 GB.
I didn't know whether to put this as a bug or in support, however, since I had no error log, it's going in Support.