Gallery handles them just as well if not better. Before I fully implemented it, I did a mass import of over 45,000 images and had it thumbnail on the fly. Flawless once I turned the PHP timeout to a very very long number.
For free, it's great. For support, you are better off shooting yourself. The few issues I had with Gallery I ended up resolving myself by recoding some of the modules. Paying members get horrid support as well. But like I said, for a free product don't expect support.
I tried Photopost and it ran less efficiently on my Dual Xeon system.