Is it normal that 8000 rows takes 20 seconds to recalculate after every edit Formula Help

Not normal. 8,000 rows should feel instant, so something in there is either volatile or scanning whole columns. The order I check:

• Formulas referencing A:A instead of A2:A8000. Fifteen columns of SUMIFS over full columns means a million row scan per formula, per recalculation.
• Volatile functions: OFFSET, INDIRECT, TODAY, NOW, RAND. Any one of them forces the whole workbook to recalculate on every keystroke.
• Conditional formatting applied to entire columns, or rules that multiplied when people copied rows. Open the rules manager — I have seen 4,000 rules in a sheet that needed three.
• Array formulas or SUMPRODUCT over full columns, same problem as the first point.
  Fix those and it drops under a second.

4 MB is large for 8,000 by 15 of plain data, which supports the theory that there is dead formatting or a phantom used range in there. A clean file of that shape is usually well under a megabyte.

As a stopgap, set calculation to manual and press F9 when you want it updated. Fine while diagnosing, dangerous as a permanent state because sooner or later you will screenshot stale numbers.

Move it to a database if it is that slow.