diff --git a/lisp/lib/buffers.el b/lisp/lib/buffers.el
index 93816f6dc..bbc360110 100644
--- a/lisp/lib/buffers.el
+++ b/lisp/lib/buffers.el
@@ -91,12 +91,12 @@ If no project is active, return all buffers."
 ;;;###autoload
 (defun doom-special-buffer-p (buf)
   "Returns non-nil if BUF's name starts and ends with an *."
-  (equal (substring (buffer-name buf) 0 1) "*"))
+  (char-equal ?* (aref (buffer-name buf) 0)))
 
 ;;;###autoload
 (defun doom-temp-buffer-p (buf)
   "Returns non-nil if BUF is temporary."
-  (equal (substring (buffer-name buf) 0 1) " "))
+  (char-equal ?\s (aref (buffer-name buf) 0)))
 
 ;;;###autoload
 (defun doom-visible-buffer-p (buf)
@@ -111,12 +111,14 @@ If no project is active, return all buffers."
 ;;;###autoload
 (defun doom-non-file-visiting-buffer-p (buf)
   "Returns non-nil if BUF does not have a value for `buffer-file-name'."
-  (not (buffer-file-name buf)))
+  (not (buffer-file-name (or (buffer-base-buffer buf) buf))))
 
 ;;;###autoload
 (defun doom-real-buffer-list (&optional buffer-list)
   "Return a list of buffers that satisfy `doom-real-buffer-p'."
-  (cl-remove-if-not #'doom-real-buffer-p (or buffer-list (doom-buffer-list))))
+  (cl-loop for buf in (or buffer-list (doom-buffer-list))
+           if (doom-real-buffer-p buf)
+           collect buf))
 
 ;;;###autoload
 (defun doom-real-buffer-p (buffer-or-name)
@@ -160,15 +162,13 @@ See `doom-real-buffer-p' for details on what that means."
   "Return a list of buffers whose `major-mode' is `eq' to MODE(S).
 
 If DERIVED-P, test with `derived-mode-p', otherwise use `eq'."
-  (let ((modes (ensure-list modes)))
-    (cl-remove-if-not (if derived-p
-                          (lambda (buf)
-                            (apply #'provided-mode-derived-p
-                                   (buffer-local-value 'major-mode buf)
-                                   modes))
-                        (lambda (buf)
-                          (memq (buffer-local-value 'major-mode buf) modes)))
-                      (or buffer-list (doom-buffer-list)))))
+  (cl-loop with modes = (ensure-list modes)
+           for buf in (or buffer-list (doom-buffer-list))
+           for mode = (buffer-local-value 'major-mode buf)
+           if (if derived-p
+                  (apply #'provided-mode-derived-p mode modes)
+                (memq mode modes))
+           collect buf))
 
 ;;;###autoload
 (defun doom-visible-windows (&optional window-list)
@@ -187,20 +187,23 @@ If DERIVED-P, test with `derived-mode-p', otherwise use `eq'."
                    if (window-list frame)
                    nconc (mapcar #'window-buffer it)))))
     (if buffer-list
-        (cl-delete-if (lambda (b) (memq b buffer-list))
-                      buffers)
-      (delete-dups buffers))))
+        (cl-loop for buf in buffers
+                 unless (memq buf buffer-list)
+                 collect buffers)
+      buffers)))
 
 ;;;###autoload
 (defun doom-buried-buffers (&optional buffer-list)
   "Get a list of buffers that are buried."
-  (cl-remove-if #'get-buffer-window (or buffer-list (doom-buffer-list))))
+  (cl-loop for buf in (or buffer-list (doom-buffer-list))
+           unless (doom-visible-buffer-p buf)
+           collect buf))
 
 ;;;###autoload
 (defun doom-matching-buffers (pattern &optional buffer-list)
   "Get a list of all buffers that match the regex PATTERN."
   (cl-loop for buf in (or buffer-list (doom-buffer-list))
-           when (string-match-p pattern (buffer-name buf))
+           if (string-match-p pattern (buffer-name buf))
            collect buf))
 
 ;;;###autoload
diff --git a/lisp/lib/files.el b/lisp/lib/files.el
index 5a9d37d83..f5a153216 100644
--- a/lisp/lib/files.el
+++ b/lisp/lib/files.el
@@ -45,6 +45,7 @@ This is used by `file-exists-p!' and `project-file-exists-p!'."
 Ignores `nil' elements in SEGMENTS, and is intended as a fast compromise between
 `expand-file-name' (slow, but accurate), `file-name-concat' (fast, but
 inaccurate)."
+  (declare (side-effect-free t))
   ;; PERF: An empty `file-name-handler-alist' = faster `expand-file-name'.
   (let (file-name-handler-alist)
     (expand-file-name
@@ -69,7 +70,9 @@ If the glob ends in a slash, only returns matching directories."
          file-name-handler-alist
          (path (apply #'file-name-concat segments)))
     (if (string-suffix-p "/" path)
-        (cl-delete-if-not #'file-directory-p (file-expand-wildcards (substring path 0 -1)))
+        (cl-loop for file in (file-expand-wildcards (substring path 0 -1))
+                 if (file-directory-p file)
+                 collect file)
       (file-expand-wildcards path))))
 
 ;;;###autoload