First question is do you mean 10,000+ rows or is this really an issue that you’re seeing with 10 rows?
If it’s with just 10 rows, I would think there must be a fairly inefficient iterative formula somewhere in the doc causing this. Even known calculation intensive solutions, like previous row formulas, don’t show themselves as slow at just 10 rows.
There is a screenshot in this post that will show how you can run a calculations analyzer to see what formulas may be taking a good bit of time.
If that doesn’t give you any hints, it might be worth writing into the Support Team and sharing a link to the doc so we can check it out there.
As for improvements to performance, we have see big dips in both doc size and time it takes to run calculations across nearly all docs on our system. That doesn’t mean that this affects every single formula though. Coda has infinite possibilities and it’s still possible to write formulas that are time consuming.