FTP is just HTTP only it transfers the file instead of the generated text. Some servers will disconnect you after a certain period of inactivity which is usually 15 minutes. Make sure you are using the correct password as if it is incorrect your ip may be blocked by the specific server you are hosted on, for a period of time. Check both of these and if they are not at fault then ensure you are not running a faulty script or using too much of your sites allocated resources (CPU Memory or bandwidth). If all of these are correct then submit a ticket it may be a simple issue.
Before you blame 000webhost, check the download speed of your internet connection. If it is under 12mb how do you think your site will load fast? My one is 12 mb and I had a site with 000webhost, it took 5 sec for my site to load.
I've also never had any problems with 000Webhost. As tpolis said; it's probably your internet connection. Try www.speedtest.net to find out what it is. If it's anything below around 10 then your site will take quite a long time to load.