Remove unnecessary conversion from list of strings to string

This has made the code a lot more performant with large directories.

After the above removal, the (mapcar #'shell-quote-argument) was
removed because it was causing issues with recursive operation - many
directories ended up being left out, and sxiv complained about not
being able to find them.

CHANGELOG.md

@@ -4,4 +4,8 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+### Fixed
+* Slow startup/freezing on large directories
+
 ## [0.1.0] - 2020-01-12

README.md

@@ -25,7 +25,6 @@ Run it from a text file containing one file name per line to open the listed fil
 7. What should be the behavior when we open Dired-marked files, then mark files within sxiv?
 
 ## Limitations
-* Currently falls flat if run in directories with a huge number of images.
 * `sxiv-dired-marked-files-p` doesn't work as intended with non '*' markers (e.g. C or D)
 
 ## Comparison with [picpocket](https://github.com/johanclaesson/picpocket)

sxiv.el

@@ -75,21 +75,14 @@ the files listed."
          (recurse (or prefix
                       (-every? #'file-directory-p paths)))
          ;; remove directories if not running recursively
-         (paths   (->> (if recurse
-                           paths
-                         (seq-remove #'file-directory-p paths))
-                       (mapcar #'shell-quote-argument)
-                       (--reduce (concat acc " " it))))
+         (paths   (if recurse
+                      paths
+                    (seq-remove #'file-directory-p paths)))
          (recurse (if recurse "-r" ""))
          (proc    (make-process :name "sxiv"
                                 :buffer "sxiv"
                                 :command
-                                (list shell-file-name
-                                      shell-command-switch
-                                      (concat "sxiv -afo "
-                                              recurse
-                                              " -- "
-                                              paths))
+                                (apply #'list "sxiv" "-afo" recurse "--" paths)
                                 :connection-type 'pipe
                                 :stderr "sxiv-errors")))
     (setq sxiv--directory default-directory)