After very careful investigation we have noticed that our cloud system is very overloaded with DNS file zone files. As Host1Free is getting bigger and bigger file zone files are growing very fast. In this case storage system can't cope with the zone files (as it always needs to search them).
In this case we will separate the DNS server from cloud to the psychical server with 15K rpm of hard drives, to avoid the delay refreshing and accessing your website.
Sorry for any inconvenience caused, but it took us some time to detect the problem. Hopefully this will be solved after the relocation.