diff --git a/pkg/commands/patch/patch.go b/pkg/commands/patch/patch.go
index 767f3cd89..74742f282 100644
--- a/pkg/commands/patch/patch.go
+++ b/pkg/commands/patch/patch.go
@@ -183,6 +183,35 @@ func (self *Patch) OldLineNumberOfLine(idx int) int {
 	return hunk.oldStart + offset
 }
 
+// LineNumbersOfLines returns what LineNumberOfLine and OldLineNumberOfLine return for
+// each line of the patch. It numbers all of them in one pass, whereas calling those
+// two for every line takes time quadratic in the length of a hunk.
+func (self *Patch) LineNumbersOfLines() (newLineNumbers []int, oldLineNumbers []int) {
+	newLineNumbers = make([]int, 0, self.LineCount())
+	oldLineNumbers = make([]int, 0, self.LineCount())
+	for range self.header {
+		newLineNumbers = append(newLineNumbers, 1)
+		oldLineNumbers = append(oldLineNumbers, 1)
+	}
+	for _, hunk := range self.hunks {
+		newLineNumber, oldLineNumber := hunk.newStart, hunk.oldStart
+		// The hunk's header line has the numbers of the hunk's first line.
+		newLineNumbers = append(newLineNumbers, newLineNumber)
+		oldLineNumbers = append(oldLineNumbers, oldLineNumber)
+		for _, line := range hunk.bodyLines {
+			newLineNumbers = append(newLineNumbers, newLineNumber)
+			oldLineNumbers = append(oldLineNumbers, oldLineNumber)
+			if line.Kind == ADDITION || line.Kind == CONTEXT {
+				newLineNumber++
+			}
+			if line.Kind == DELETION || line.Kind == CONTEXT {
+				oldLineNumber++
+			}
+		}
+	}
+	return newLineNumbers, oldLineNumbers
+}
+
 // Returns hunk index containing the line at the given patch line index
 func (self *Patch) HunkContainingLine(idx int) int {
 	for hunkIdx, hunk := range self.hunks {
diff --git a/pkg/commands/patch/patch_test.go b/pkg/commands/patch/patch_test.go
index e22876b19..dffceece2 100644
--- a/pkg/commands/patch/patch_test.go
+++ b/pkg/commands/patch/patch_test.go
@@ -838,6 +838,37 @@ func TestOldLineNumberOfLine(t *testing.T) {
 	}
 }
 
+func TestLineNumbersOfLines(t *testing.T) {
+	scenarios := []struct {
+		testName string
+		patchStr string
+	}{
+		{"simpleDiff", simpleDiff},
+		{"twoHunks", twoHunks},
+		{"twoHunksWithMoreAdditionsThanRemovals", twoHunksWithMoreAdditionsThanRemovals},
+		{"twoChangesInOneHunk", twoChangesInOneHunk},
+		{"consecutiveDeletions", consecutiveDeletions},
+		{"renameWithModificationDiff", renameWithModificationDiff},
+		{"addNewlineToEndOfFile", addNewlineToEndOfFile},
+		{"newFile", newFile},
+		{"deletedFile", deletedFile},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			patch := Parse(s.patchStr)
+			newLineNumbers, oldLineNumbers := patch.LineNumbersOfLines()
+
+			assert.Len(t, newLineNumbers, patch.LineCount())
+			assert.Len(t, oldLineNumbers, patch.LineCount())
+			for idx := range patch.LineCount() {
+				assert.Equal(t, patch.LineNumberOfLine(idx), newLineNumbers[idx], "new line number of line %d", idx)
+				assert.Equal(t, patch.OldLineNumberOfLine(idx), oldLineNumbers[idx], "old line number of line %d", idx)
+			}
+		})
+	}
+}
+
 func TestGetNextStageableLineIndex(t *testing.T) {
 	type scenario struct {
 		testName  string
diff --git a/pkg/gui/controllers/helpers/diff_line_parser.go b/pkg/gui/controllers/helpers/diff_line_parser.go
index 39d99c9ec..1a019bf1c 100644
--- a/pkg/gui/controllers/helpers/diff_line_parser.go
+++ b/pkg/gui/controllers/helpers/diff_line_parser.go
@@ -272,6 +272,7 @@ func parseFileSection(fileLines []string, endsTheBuffer bool) []bufferLineParse
 		return result
 	}
 	patchLines := p.Lines()
+	newLineNumbers, oldLineNumbers := p.LineNumbersOfLines()
 	for i := range fileLines {
 		if i >= len(patchLines) {
 			break
@@ -279,10 +280,10 @@ func parseFileSection(fileLines []string, endsTheBuffer bool) []bufferLineParse
 		parsed := parsedDiffLine{
 			Path:    relPath,
 			Type:    diffLineTypeForKind(patchLines[i].Kind),
-			NewLine: p.LineNumberOfLine(i),
+			NewLine: newLineNumbers[i],
 		}
 		if parsed.Type == types.DiffLineDeleted {
-			parsed.OldLine = p.OldLineNumberOfLine(i)
+			parsed.OldLine = oldLineNumbers[i]
 		}
 		result[i] = bufferLineParse{parsed, true}
 	}