Subject: Re: Latest from Howard Marks
it appears that, given my own tax situation, a portfolio that pays taxes on capital gains every year at the long-term rate needs to outperform a portfolio taxed only once (at the end)

This is clear on its face. Simple math.

If you pay tax every year, the annual return is reduced by that tax amount.
15% tax on a 10% gain is net CAGR of 8.5%.
That tax eats away at the return every year. The dollars you remove to pay the tax won't continue to compound.

Calculate using 10% CAGR, 15% tax, over 20 years.

Pay tax each year, $100 grows to $511

Pay tax at end, $100 grows to $672, minus 15% of the $572 gain = $587.