yes experiencing this same annoying issue aswel

linux os, php version latest

using php's ftp function to upload files is way slower than using any other ftp client to transfer files from from the same two servers.

Not sure why but its very annoying that there doesn't seem to be any way php ini settings to fix this.

please fix it soon

I have the same problem with cUrl (posting files via HTTP), on Windows Server 2008 
and 2012 and Windows 7. Always about 10x slower than possible on the server side 
(If the server could send 10 mbps I get 1 mbps, even if this is 100% of my 
capacity).

I have seen the same issue, windows 2008. Upload speeds are much slower than other platforms. I did find this bug reference in libcurl which may be relevant
http://sourceforge.net/p/curl/bugs/1188/?page=1

The problem still exists and is very annoying.
PHP FTP upload functionality seems to be almost unusable because of this.

Is there any progress? I have the same issue... Thanks.

Is there any progress? I have found the same issue.

I can confirm that ftp_put() uploads are slow on Windows.
Increasing the FTP_BUFSIZE[1] to a value just a bit smaller than
SO_SNDBUF (64KiB on my system), shows a performance improvement of
about 30%.  However, uploading from WSL1 still takes only half the
time.  There might be room for (further) improvements on Windows,
but maybe this is just a Windows limitation.  This needs further
investigation.

Note the ftp_put() relies on select(3), so performance is
certainly not optimal on either operating system.

[1] <https://github.com/php/php-src/blob/php-7.4.15/ext/ftp/ftp.h#L38>

Bug showed after complete upgrade (kernel, libraries, php) of our production backup-copying system.
System is connecting to FTP inside our LAN and is used to push backup video files (250+TiB in total, daily throughput approx. 160GiB) to external backup over 1Gbit infrastructure.

Before upgrade, php ftp performance was comparable to midnight commander ftp client
 ie. approx. 80MBps-90MBps.
After upgrade php performance degraded to approx. 1/6 of mc ftp which is approx. 15MBps.

I have serious backlog of 50-60TiB which i need to push through FTP and this performance regression showing after upgrade is real pain ...

command used in php script is ftp_push
there is no difference in enabling FTP_PASSIVE 
(problem manifests in active and passive mode)
mode used is FTP_BINARY

i have done some tests now and behavior is observed under:
php-7.4.14
php-7.2.34
php-5.6.29
php-5.5.37

i have tried to compile 
php-7.4.14 with FTP_BUFSIZE 65536 in ftp.h
however there seems to be no difference in behavior.

My guess is this may be problem of some underlying library which is being used in php and not being used in other clients

Any help would be greatly appreciated.

Workaround found:

Under php 7.4.19 problem persists.

However, under the very same version and build of php,
 where php function ftp_put() has unsatisfactory performance of 15MBps,
calling cURL to do the same job has performance comparable to other FTP clients i.e. 80MBps.

I therefore believe, this performance regression is limited to FTP extension of PHP

code:
ftp_put($this->FTPHANDLE,$dest,$src,FTP_BINARY)

code (return values checks redacted out):

$curlhandle = curl_init()
$srcfilehandle = fopen($src,'r'))
curl_setopt($curlhandle, CURLOPT_URL, 'ftp://'.$user.':'.$pass.'@'.$url.'/'.$dest);
curl_setopt($curlhandle, CURLOPT_UPLOAD, 1);
curl_setopt($curlhandle, CURLOPT_FTP_USE_EPSV, TRUE);
curl_setopt($curlhandle, CURLOPT_TRANSFERTEXT, FALSE);
curl_setopt($curlhandle, CURLOPT_INFILE, $srcfilehandle);
curl_setopt($curlhandle, CURLOPT_INFILESIZE, filesize($src));
curl_exec($curlhandle);