diff --git a/.jules/bolt.md b/.jules/bolt.md
index a9253e7..cf9c417 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -12,3 +12,11 @@
 ## 2024-07-08 - URL Encoding String Allocation Bottleneck
 **Learning:** `byte.toString(16).padStart(2, '0').toUpperCase()` inside a loop allocating up to 3 strings per reserved byte in a hot path causes significant GC pressure. This is a common but dangerous anti-pattern in Kotlin when processing large strings or numerous files in directory crawlers.
 **Action:** Replace chained string operations with direct character mapping and bitwise operations (`ushr`, `and`) when building formatted hex output, which avoids intermediate string creation entirely. Ensure 100% branch coverage with test inputs spanning both < 10 and > 9 hex values.
+
+## 2024-07-29 - Excessive File Object and I/O Operations in Filter Loops
+**Learning:** In directory crawlers, calling `.listFiles()` loads `File` objects for every item, and subsequently calling `it.toPath()` and expensive I/O operations (`Files.isDirectory`, `Files.isSymbolicLink`) *before* checking exclusions creates significant overhead on large directories with many excluded files.
+**Action:** Always check file names against exclusion sets (`if (fileName !in exclude)`) *before* allocating `Path` objects or executing I/O checks.
+
+## 2024-07-29 - Unnecessary Sorting in Set Accumulation
+**Learning:** Calling `.sorted()` on a directory listing (`curr_dir.list()?.sorted()?.forEach`) before adding elements to a `Set` or checking against a list of RegExes wastes O(N log N) time and allocates unnecessary arrays.
+**Action:** Omit `.sorted()` when order is irrelevant (e.g., when populating an exclusion `Set`) and use `.any` to short-circuit regex checking.
diff --git a/src/main/kotlin/html4tree/main.kt b/src/main/kotlin/html4tree/main.kt
index c4877e2..a9de627 100644
--- a/src/main/kotlin/html4tree/main.kt
+++ b/src/main/kotlin/html4tree/main.kt
@@ -139,13 +139,10 @@ fun process_ignore_file(curr_dir: File): Set<String> {
            }
        }
 
-       curr_dir.list()?.sorted()?.forEach {
-           val current = it
-           ignored_regexes.forEach { regex ->
-              if(regex.matches(current)){
-                 files_to_exclude.add(current)
-              }
-         }
+       curr_dir.list()?.forEach { current ->
+           if (ignored_regexes.any { it.matches(current) }) {
+               files_to_exclude.add(current)
+           }
        }
     }
 
@@ -225,14 +222,17 @@ fun process_dir(curr_dir: File){
         val dir_files: MutableList<File> = curr_dir.listFiles()?.toMutableList() ?: mutableListOf()
         dir_files.sortWith(compareBy ({it.name}) )
         dir_files.forEach {
-           val isLinkedDirectory = Files.isDirectory(it.toPath(), LinkOption.NOFOLLOW_LINKS)
-           if((it.getName() !in exclude) && (isLinkedDirectory || !it.isDirectory()) && !Files.isSymbolicLink(it.toPath())) {
-              val fileName = it.getName()
-              val encodedHref = if (isLinkedDirectory) { "./${fileName.urlEncodePath()}/" } else { "./${fileName.urlEncodePath()}" }
-              val ariaLabel = "${fileName} ${if (isLinkedDirectory) { "디렉토리" } else { "파일" }}".escapeHtml()
-              val icon = if (isLinkedDirectory) { "&#128193;" } else { "&rtrif;" }
-              l.append("""          <li><a style="display:block; width:100%" href="${encodedHref}" aria-label="${ariaLabel}"><span aria-hidden="true">${icon}</span> ${fileName.escapeHtml()}</a></li>""")
-              l.append('\n')
+           val fileName = it.getName()
+           if (fileName !in exclude) {
+               val path = it.toPath()
+               val isLinkedDirectory = Files.isDirectory(path, LinkOption.NOFOLLOW_LINKS)
+               if ((isLinkedDirectory || !it.isDirectory()) && !Files.isSymbolicLink(path)) {
+                  val encodedHref = if (isLinkedDirectory) { "./${fileName.urlEncodePath()}/" } else { "./${fileName.urlEncodePath()}" }
+                  val ariaLabel = "${fileName} ${if (isLinkedDirectory) { "디렉토리" } else { "파일" }}".escapeHtml()
+                  val icon = if (isLinkedDirectory) { "&#128193;" } else { "&rtrif;" }
+                  l.append("""          <li><a style="display:block; width:100%" href="${encodedHref}" aria-label="${ariaLabel}"><span aria-hidden="true">${icon}</span> ${fileName.escapeHtml()}</a></li>""")
+                  l.append('\n')
+               }
            }
         }