In this question Schnorr vs ECDSA I see in the Peter Wuille's answer the following comment about Schnorr signature batch validation: "Improving verification speed, by supporting batch validation of all signatures in a block at once (for a fraction of the speed of validating them individually)."
However, looking at the chart in the BIP here https://github.com/sipa/bips/blob/bip-schnorr/bip-schnorr.mediawiki#Batch_verification it seems that savings are actually close a factor of log(n). In other words, for about 10,000 signatures the time savings are about 2.5X. I know that technically that is a fraction, but it seemed that the implication was that the improvement was more dramatic. Is there something I am missing? Also, what is the actual time in clock cycles that was a starting point for one Schnorr signature verification? Thank you.