1,005. Labors That Can Be Performed Before Yom Tov
Shvisas Yom Tov 1:6
The Sages did not prohibit transferring items between domains on yom tov even if the items could have been transferred beforehand. This is in order to increase one’s holiday joy, so that a person can send and bring anything he likes and fulfill his desires without feeling restricted. Other labors that can be performed before yom tov require much more effort, so they may not be performed on yom tov.
Shvisas Yom Tov 1:7
Accordingly, one may not harvest, thresh, winnow, separate, grind or sift on yom tov. These and similar labors can be performed before yom tov without a person incurring a loss or achieving inferior results.