Improve method so it's 200% faster when there are many many rows
diff --git a/R/util.R b/R/util.R
index f63e0c0..f201bda 100644
--- a/R/util.R
+++ b/R/util.R
@@ -124,7 +124,7 @@
     empty_times <- dup_index[i] - 1
     new_row <- str_replace(
       dup_row, "&",
-      paste(c("&", rep("\\\\\\\\empty", empty_times)), collapse = ""))
+      paste0("&\\\\\\\\vphantom\\\\{", empty_times, "\\\\}"))
     kable_input <- str_replace(kable_input, dup_row, new_row)
     table_info$contents[i] <- new_row
   }