In case of a Swiss resident, tax optimization includes (at least) two things: (i) less non-reclaimable withholding tax on dividends and (ii) less dividends which are taxed as income. So it is for example possible to move a segment that pays more dividends into a tax-sheltered account (3a funds at finpension/VIAC).
Dataset 2: % of non-reclaimable witholding taxes on dividends and dividend yields for some “whole world” (with and without emerging markets) funds.