Check for deadline only if there is a valid value for it.

This shaves a few percent off of the speedtest, because calling NSDate’s -timeIntervalSinceReferenceDate for every iteration of the loop is expensive and unnecessary if there is no deadline.

DiffMatchPatch.m

@@ -730,7 +730,9 @@ - (NSMutableArray *)diff_bisectOfOldString:(NSString *)_text1
                        if (text2_buffer != NULL) free(text2_buffer);\
                        free(v1);\
                        free(v2);
-
+
+  BOOL validDeadline = (deadline != [[NSDate distantFuture] timeIntervalSinceReferenceDate]);
+
   CFStringRef text1 = (CFStringRef)_text1;
   CFStringRef text2 = (CFStringRef)_text2;
 
@@ -772,7 +774,7 @@ - (NSMutableArray *)diff_bisectOfOldString:(NSString *)_text1
   NSMutableArray *diffs;
   for (CFIndex d = 0; d < max_d; d++) {
     // Bail out if deadline is reached.
-    if ([NSDate timeIntervalSinceReferenceDate] > deadline) {
+    if (validDeadline && ([NSDate timeIntervalSinceReferenceDate] > deadline)) {
       break;
     }