Reduce frequency of progress indicator's output

Only print the progress indicator every 65th loop iteration to reduce
CPU usage.

This mainly affect the terminal's CPU usage and not fdupes.
Mostly noticeable for large directories

fdupes.c

@@ -57,6 +57,10 @@
   #include "xdgbase.h"
 #endif
 
+// Only print progress every Nth loop iteration
+// Should be a (multiple of 4) + 1
+#define PROGRESS_DIVIDER 65
+
 char *program_name;
 
 long long minsize = -1;
@@ -302,8 +306,12 @@ int grokdir(char *dir, file_t **filelistp, struct stat *logfile_status)
 
     if (strcmp(dirinfo->d_name, ".") && strcmp(dirinfo->d_name, "..")) {
       if (!ISFLAG(flags, F_HIDEPROGRESS)) {
-	fprintf(stderr, "\rBuilding file list %c ", indicator[progress]);
-	progress = (progress + 1) % 4;
+        // Only print progress every n-th file to reduce (terminal) CPU use
+        // (multiple of 4 + 1 so the indicator still alternate properly)
+        if ( progress % PROGRESS_DIVIDER == 0 ) {
+          fprintf(stderr, "\rBuilding file list %c ", indicator[progress % 4]);
+        }
+        progress++;
       }
 
       newfile = (file_t*) malloc(sizeof(file_t));
@@ -1855,8 +1863,11 @@ int main(int argc, char **argv) {
     curfile = curfile->next;
 
     if (!ISFLAG(flags, F_HIDEPROGRESS)) {
-      fprintf(stderr, "\rProgress [%d/%d] %d%% ", progress, filecount,
-       (int)((float) progress / (float) filecount * 100.0));
+      // Only print progress every 65th file to reduce (terminal) CPU used to display progress
+      if ( progress % PROGRESS_DIVIDER == 0 ) {
+        fprintf(stderr, "\rProgress [%d/%d] %d%% ", progress, filecount,
+         (int)((float) progress / (float) filecount * 100.0));
+      }
       progress++;
     }
   }