That seems true from my experience, that it reloads the texture each render. That won't answer your question about what's happenng with your program freezing. I have twice the RAM but get the same problem sometimes, there is a freeze while rendering that doesn't register as 'not responding' if you c/a/d. Other people have told me it happens to them too. Maybe a bug?

"Your work is to keep cranking the flywheel that turns the gears that spin the belt in the engine of belief that keeps you and your desk in midair."

Annie Dillard