For context, all of our virtual instruments load the individual samples (audio files) that are needed for the preset that is being used from disk into RAM.
Generally, libraries made for Superior Drummer 3 load under 16GB of samples into RAM in your project. But as is with everything Superior Drummer 3, the sky is the limit!
The preset engineers rarely activate full bleed on all mic channels. If you do, you will notice that the RAM usage of SD3 increases significantly. For example the Default preset in Stories SDX (Main) loads around 3.7GB into RAM, but if you enable full bleed for all mic channels in that preset, that number increases to 18GB.
Read more about how you can enable bleed for a channel in the SD3 mixer here in the manual:
https://www.toontrack.com/manual/superior-drummer-3/5/5-1-mixer-tab-header-bar/5-1-6-mixer-properties