diff --git a/copyparty/__main__.py b/copyparty/__main__.py
index d8937008..119cd7bf 100755
--- a/copyparty/__main__.py
+++ b/copyparty/__main__.py
@@ -869,6 +869,7 @@ def add_upload(ap):
     ap2.add_argument("--df", metavar="GiB", type=float, default=0, help="ensure \033[33mGiB\033[0m free disk space by rejecting upload requests")
     ap2.add_argument("--sparse", metavar="MiB", type=int, default=4, help="windows-only: minimum size of incoming uploads through up2k before they are made into sparse files")
     ap2.add_argument("--turbo", metavar="LVL", type=int, default=0, help="configure turbo-mode in up2k client; [\033[32m-1\033[0m] = forbidden/always-off, [\033[32m0\033[0m] = default-off and warn if enabled, [\033[32m1\033[0m] = default-off, [\033[32m2\033[0m] = on, [\033[32m3\033[0m] = on and disable datecheck")
+    ap2.add_argument("--u2j", metavar="JOBS", type=int, default=2, help="web-client: number of file chunks to upload in parallel; 1 or 2 is good for low-latency (same-country) connections, 4-8 for android clients, 16-32 for cross-atlantic (max=64)")
     ap2.add_argument("--u2sort", metavar="TXT", type=u, default="s", help="upload order; [\033[32ms\033[0m]=smallest-first, [\033[32mn\033[0m]=alphabetical, [\033[32mfs\033[0m]=force-s, [\033[32mfn\033[0m]=force-n -- alphabetical is a bit slower on fiber/LAN but makes it easier to eyeball if everything went fine")
     ap2.add_argument("--write-uplog", action="store_true", help="write POST reports to textfiles in working-directory")
 
diff --git a/copyparty/httpcli.py b/copyparty/httpcli.py
index 15eb703b..b8feda96 100644
--- a/copyparty/httpcli.py
+++ b/copyparty/httpcli.py
@@ -3966,6 +3966,7 @@ class HttpCli(object):
             "dsort": vf["sort"],
             "themes": self.args.themes,
             "turbolvl": self.args.turbo,
+            "u2j": self.args.u2j,
             "idxh": int(self.args.ih),
             "u2sort": self.args.u2sort,
         }
diff --git a/copyparty/web/browser.js b/copyparty/web/browser.js
index f49a017a..f152b152 100644
--- a/copyparty/web/browser.js
+++ b/copyparty/web/browser.js
@@ -1077,7 +1077,7 @@ ebi('op_up2k').innerHTML = (
 	'	<tr>\n' +
 	'		<td class="c" data-perm="read">\n' +
 	'			<a href="#" class="b" id="nthread_sub">&ndash;</a><input\n' +
-	'				class="txtbox" id="nthread" value="2" tt="' + L.ut_par + '"/><a\n' +
+	'				class="txtbox" id="nthread" value="" tt="' + L.ut_par + '"/><a\n' +
 	'				href="#" class="b" id="nthread_add">+</a><br />&nbsp;\n' +
 	'		</td>\n' +
 	'	</tr>\n' +
diff --git a/copyparty/web/up2k.js b/copyparty/web/up2k.js
index 1917302c..1e43e074 100644
--- a/copyparty/web/up2k.js
+++ b/copyparty/web/up2k.js
@@ -852,7 +852,7 @@ function up2k_init(subtle) {
 
     setmsg(suggest_up2k, 'msg');
 
-    var parallel_uploads = icfg_get('nthread'),
+    var parallel_uploads = ebi('nthread').value = icfg_get('nthread', u2j),
         uc = {},
         fdom_ctr = 0,
         biggest_file = 0;
@@ -2685,7 +2685,11 @@ function up2k_init(subtle) {
             }
 
             parallel_uploads = v;
-            swrite('nthread', v);
+            if (v == u2j)
+                localStorage.removeItem('nthread');
+            else
+                swrite('nthread', v);
+
             clmod(obj, 'err');
             return;
         }
@@ -2699,7 +2703,7 @@ function up2k_init(subtle) {
             parallel_uploads = 16;
 
         obj.value = parallel_uploads;
-        bumpthread({ "target": 1 })
+        bumpthread({ "target": 1 });
     }
 
     function tgl_fsearch() {
diff --git a/copyparty/web/util.js b/copyparty/web/util.js
index d830565a..593443b5 100644
--- a/copyparty/web/util.js
+++ b/copyparty/web/util.js
@@ -931,7 +931,7 @@ function fcfg_get(name, defval) {
         val = parseFloat(sread(name));
 
     if (!isNum(val))
-        return parseFloat(o ? o.value : defval);
+        return parseFloat(o && o.value !== '' ? o.value : defval);
 
     if (o)
         o.value = val;