I can only report my difficulties and my findings when I locate a "solution."
Apparently a ! in a folder name causes issues, at least on my setup.
Also I added the following to the "Additional" tab:
$cache_dirs = true;
$show_counter_in_jstree=false;
$show_number_of_pic = false;
$show_count_views = false;
$use_random_image_for_folder=false;
I already had...
$use_cache_with_dir = true;
set, so i'll see if that brings up initial performance or not.
eta: also Debug keeps catching these 4 errors as a group
04.02.2019 3:39:40 (en) - ERROR 2 in G:\xampp\htdocs\twg\inc\readxml.inc.php, line 676: fopen(): Filename cannot be empty
04.02.2019 3:39:40 (en) - Please check the file: . Seems php cannot read/write/create it properly. TWG tries to rename the file to .bak
04.02.2019 3:39:40 (en) - ERROR 2 in G:\xampp\htdocs\twg\inc\readxml.inc.php, line 781: rename(,.bak): Invalid argument
04.02.2019 3:39:40 (en) - ERROR 2 in G:\xampp\htdocs\twg\inc\readxml.inc.php, line 607: Invalid argument supplied for foreach()
No idea where to even look to figure out what's causing them.