Fix slowness of posframe

Fixes #192

ace-window-posframe.el

@@ -4,8 +4,15 @@
 
 (defun aw--lead-overlay-posframe (path leaf)
   (let* ((wnd (cdr leaf))
-         (str (apply #'string path))
-         (bufname (format "*aw-posframe-buffer-%s*" (gensym))))
+         (str (format "%s" (apply #'string path)))
+         ;; It's important that buffer names are not unique across
+         ;; multiple invocations: posframe becomes very slow when
+         ;; creating new frames, and so being able to reuse old ones
+         ;; makes a huge difference. What defines "able to reuse" is
+         ;; something like: a frame exists which hasn't been deleted
+         ;; (with posframe-delete) and has the same configuration as
+         ;; the requested new frame.
+         (bufname (format "*aw-posframe-buffer-%s*" path)))
     (with-selected-window wnd
       (push bufname aw--posframe-frames)
       (posframe-show bufname
@@ -16,7 +23,9 @@
                      :background-color (face-background 'aw-leading-char-face)))))
 
 (defun aw--remove-leading-chars-posframe ()
-  (map nil #'posframe-delete aw--posframe-frames))
+  ;; Hide rather than delete. See aw--lead-overlay-posframe for why.
+  (map nil #'posframe-hide aw--posframe-frames)
+  (setq aw--posframe-frames '()))
 
 (defun ace-window-posframe-enable ()
   (setq aw--lead-overlay-fn #'aw--lead-overlay-posframe