I'm like auremcalendula and make subclips within my editing software (Vegas in my case). So no rerendering required. Although depending on source format I might have to convert it to load it into Vegas.

I do have a source prep process that I can make clips as part of, but generally all I do is trim credits there (I basically follow the process at https://www.animemusicvideos.org/guides/avtech31/, which is very old and based on the idea you will be ripping your own source!)