Changing the initial size can improve performance, but only to a certain extent. I have a feeling you wouldn't see any real difference in speed between 10000 initial size and 75000 initial size, even with a lot of items.
Keep in mind that the initial size is best at 10% of the number of expected items. You currently have 23705 items. So your initial size should only be something like 2500 anyhow, or even 3000 if you want to assume you'll have another 6000+ items added. That's way below the 10000 limit.
Btw, this isn't a bug and should not be in the bugs forum. If you want something changed, it should go in the feature request forum.
Also, I hope you're not allowing !eval to evaluate any requested identifier. Doing so can very easily compromise your system.
