diff --git a/guix-data-service/model/nar.scm b/guix-data-service/model/nar.scm
index c66e6d2..e5bc1ad 100644
--- a/guix-data-service/model/nar.scm
+++ b/guix-data-service/model/nar.scm
@@ -386,7 +386,7 @@ ORDER BY COUNT(*) DESC")
           #:key
           build-success-after
           after-id
-          (limit 2000))
+          (limit 500))
   (define query
     (string-append
      "
diff --git a/guix-data-service/substitutes.scm b/guix-data-service/substitutes.scm
index 0635122..2a6df3c 100644
--- a/guix-data-service/substitutes.scm
+++ b/guix-data-service/substitutes.scm
@@ -114,7 +114,7 @@
                          total-narinfos)
 
           (let ((filtered-narinfos
-                 (filter-map
+                 (remove!
                   (lambda (narinfo)
                     (if (> (narinfo-size narinfo)
                            %narinfo-max-size)
@@ -123,8 +123,8 @@
                                          "narinfo ~A has excessive size ~A\n"
                                          (narinfo-path narinfo)
                                          (narinfo-size narinfo))
-                          #f)
-                        narinfo))
+                          #t)
+                        #f))
                   narinfos)))
 
             (unless (null? filtered-narinfos)