Optimizing checklist for a lot of data

So I have a checklist for ~1500 items

here’s currently how I do it

  toggleOpenTimeSlot = (timeSlotId) => {
    if (this.isTimeSlotOpened(timeSlotId)) {
      this.setState({
        openedTimeSlots: this.state.openedTimeSlots.filter(
          (id) => id !== timeSlotId
        ),
      });
    } else {
      this.setState({
        openedTimeSlots: [...this.state.openedTimeSlots, timeSlotId],
      });
    }
  };

  isTimeSlotOpened = (timeSlotId) =>
    this.state.openedTimeSlots.includes(timeSlotId);

But this approach is very slow, every time I check a checkbox, it takes more than a second to rerender

I also tried something like this

 toggleOpenTimeSlot = (timeSlotId) => {
    if (this.isTimeSlotOpened(timeSlotId)) {
      this.setState((state) => {
        return {
          ...state,
          openedTimeSlots: {
            ...state.openedTimeSlots,
            [timeSlotId.toString()]: false,
          },
        };
      });
    } else {
      this.setState((state) => {
        const newOpenedTimeSlots = { ...state.openedTimeSlots };
        delete newOpenedTimeSlots[timeSlotId.toString()];

        return {
          ...state,
          openedTimeSlots: newOpenedTimeSlots,
        };
      });
    }
  };

  isTimeSlotOpened = (timeSlotId) =>
    this.state.openedTimeSlots[timeSlotId.toString()];

But it seems the performance gets worse after that