I don't have the manual handy, so this may have a trivial solution.

I noticed my 48GX seemed to be slowing down as I used it. At some point it dawned on me that the stack had hundreds of numbers on it. I'm guessing that the internal bookkeeping to pop the stack each time I enter something is slowing down the whole machine. When I cleaned out the stack by deleting one value at a time (lots of back-arrow key presses!), it seems "better."

Is this normal? Is there a single "empty the stack" command? Is there anything I should be doing as I calculate to keep the stack at a reasonable size?

I agree with some other comments that a stack bigger than 4 or 5 is unnecessary. Can I put it in a limited stack mode?