The indicator scans all CCI indicators in the period_start - period_end range.
It searches for the maximum CCI period that exceeds the cci_lev level.
The number of bars in the window greatly affects its speed, limit_shift does not help with this.

Donchian Channel (High/Low Close)
The peculiarity of this indicator is that it does not need a history. This formula has no limit on the number of periods. Being in one indicator, it can check tens of thousands of periods.
There are some minor inaccuracies. An accurate search will require additional checks, and its speed will decrease significantly.