Web server slow loading even html pages (10 seconds time to first byte)

Hello, my apache 2.x web server with suphp started loading all websites slow (before a few days it was OK and i made no config. changes). For example even a .html page loads like 10 seconds and when the page contains an image, i wait another 10 seconds for it to appear. So the problem is time to first byte (TTFB) of my web server apache.
When i restart httpd, it shows problem with mixed ports, i bet it is not related and is soft error.

time curl -v publicIPofRemotewebserver
time curl -v publicIPofLocalwebserver

first is loaded under 1s, second is 10 seconds...

 

Have you tried pinging the server to see if there's a slow connection somewhere between your computer and the server?

 

This is not the issue. Slow down is evident also via other servers like webpagetest.org and even local webserver command "curl -v hxxp://hosteddomain.tld/page.html" is delayed. curl -v hxxps://google.com is not delayed.

 

Where is the website hosted? If it's shared server you may contact the provider and ask them to check server response time because html sites should not take so much long unless there are heavy images or videos embedded on home page.

 

The issue disappeared after server restart, though if anyone have idea how to fix or discover cause without restart, please comment.

 

Anything in the error logs around the time it started being slow?

 

I can not spot exact time. it was like +-3 days.. And who knows in which log file such possible error may be on cpanel server. apache error_log is 227MB big and is since January 6. I do not want to go line by line while not knowing what i am looking for.