TI-36X Pro—Replace the batteries or just get a new one?

[Benjer]

I have a TI36X Pro with manufacturing code L-0516. In Mathprint mode it does VBlogMag's integration in about 82 seconds. In classic mode it does the same in about 36 seconds. I did a few runs in each mode and the results were consistent. I was getting the same answer he was getting so I'm assuming it's the same function his was.

Not sure why the TI gives different performances based on display mode. I did not see a similar phenomenon on the Casio.