Earlier quoted context omitted.
I had a friend who worked for one of the big Market Makers, and he told me that they would indeed turn the GC off, but what they'd do is just pre-allocate everything into bigass arrays before-hand, and have incrementers to simulate the "new" keyword. They might do this in something more or less like a threadlocal to avoid having to deal with locks or race conditions or anything like that.
A lot of game engines do this, avoiding the cost of a malloc lookup by just allocating everything as a stack
I remember seeing a Java game engine that included a container that you were supposed to dump unused objects into to prevent GC from running in the middle of a level. At the end of the level, you could empty the container, and let the GC run during the loading screen or whatever.
It was a deliberate design choice that was surprisingly close to what the original article describes.