pythongh-145131: difflib.Differ._fancy_replace performance (re-use ratio) (python#145133)

re-use calculated ratio

Author: dg-pb

Lib/difflib.py

@@ -942,10 +942,12 @@ def _fancy_replace(self, a, alo, ahi, b, blo, bhi):
                 cruncher.set_seq1(a[i])
                 # Ordering by cheapest to most expensive ratio is very
                 # valuable, most often getting out early.
-                if (crqr() > best_ratio
-                      and cqr() > best_ratio
-                      and cr() > best_ratio):
-                    best_i, best_j, best_ratio = i, j, cr()
+                if crqr() <= best_ratio or cqr() <= best_ratio:
+                    continue
+
+                ratio = cr()
+                if ratio > best_ratio:
+                    best_i, best_j, best_ratio = i, j, ratio
 
             if best_i is None:
                 # found nothing to synch on yet - move to next j