Apache reverse proxy very slow

Hi,

I have a fresh perfect server with ubuntu running OK on a VPS.

I installed a service called ScreenConnect, which is a remote support software, it works at the port 8040.

So I did set a reverse proxy, so I can access it trough help.domain.com

I put this before the ISPconfig vhost include...

Code:

NameVirtualHost *:80
<VirtualHost *:80>
        ServerName help.domain.com
        ProxyPreserveHost On

        ProxyPass / http://127.0.0.1:8040/
        ProxyPassReverse / http://127.0.0.1:8040/
</VirtualHost>

Problem is, if I access the service in the normal way, http://server-ip:8040 it goes ok, perfect.
However if I access trough the proxy, it takes more than 15-20 seconds to load, and sometimes it fails, not loading the CSS for example.

I am missing something? What can I do to improve this??

Thanks!!!