Suddenly webserver slow down

Hi suddenly all my wordpress websites and the virtualmin control panel slow right down and even to website error appearing. I checked the log for an example :
mod_fcgid: read data timeout in 31 seconds

I have therefore extended the php timeout for the domains and this has now helped but what is stumping me is why this has just happened all of a sudden. The memory usage and disk space if very low looking at the dials in virtualmin. I tried rebooting and this didnt help. I have debian with 8gb memory (only 1 gig in use) loads of space on hard drive too.
Maybe slow SQL server i’m thinking, anyway to check/speed up?

perhaps hdd is failing?

The top command will give you hints about what is consuming resources…

OK Im now wondering if Ive been hacked. The proFTP server will not start in virtual control panel, when I try command line with: proftpd it replies with:
warning: unable to determine IP address of ‘mywebsite.net
Ive looked in the host file and there is the hostname but no IP address, should IP be in there next to hostname? I looked at the logs and there were 100’s of entries where tor.somthing trying to log in but failing with wrong un/pw .