You are, but it can still be cheaper. I calculated/simulated that quite extensively some time ago, but a very rough calculation is: I pay 11.8% corporate income tax on all profit. Marginal tax rate on income >230k is 7.3% (canton) + 13.2% (federal taxes), so 20.5% in total. If you pay yourself a salary, you pay this 20.5% on your net income, so 12.8% AHV & ALV + (1 - 6.4%) * 20.5% ~= 32%.
Dividends are only taxed at 0.5 * 7.3% + 0.7 * 13.2% = 12.89%. So the total taxes are 11.8% + (1 - 11.8%) * 13.2% ~= 23.4%
In practice, this is much more complicated to calculate correctly, because you also have to consider the pension fund (allowing tax free withdrawals up to 25% of your income, although you have to increase your income for it, which in turn increases AHV & portion of money that is taxed to normal conditions), the effects on the wealth tax, etc…
And the results might differ in other cantons, especially when they have higher corporate income taxes and higher rates for the privileged taxation of dividends.