Linking cells is taking too long

Hey guys,

I have a source sheet and a destination sheet. On the destination sheet there are some calculations that are made, and being sent back to the source sheet based on index and collcet on a specific col.

untill a few days the linking was created in a few seconds, and now it takes much longer, for about a few mintues for every row that is created in the source sheet.

The only thing I changed in the last few days was adding conditional formatting to these sheets, but even when I tried erasing them, it still takes a few mintues for every row to arrive to the destination sheet.

Is there a way it can be fixed? It's impossible to work with these sheets this way

Thank you