There's a handy shortcut available for dropping items quickly, and that is to press and hold the Drop key (Q by default); this throws items out of one's inventory at very high speed.

Unfortunately, if the Drop key is set to certain keybinds, this functionality breaks. From my testing, those keybinds include Shift, CapsLock, Alt/Option, and Control.

I found this bug because my normal keybind for Drop is Left Alt, a decision that was made necessary because of MC-22882. The only way to drop a full stack on Mac is Cntrl+Cmd+Drop, which makes Left Alt the most ergonomically sensible keybind.