XML-API nvset causing high server load

Hi, I use cpanel for last 6-9months on my vps. for that long time,i face a major from of high server load on a specific time almost everyday. this server is use for specially official email. but there is some website also which is low traffice (around 200 unique visitor total). At 10am to 5pm, my server face high load time almost 2-3days week. i tried to figure out what actually cause that load for last few months. recetly i see when server load is around 10-15, top proccess is "xml-api nvset" i dont know what is nvset and what does it do? i tried to kill those proccess but nothing help. i tried for 2-3hours by killing those proccess but again started. but at a certain time, its automatically become normal. i guess something is updating via api. i turned of all update. i buy cloudlinux too. but still same problem. My job is stack and i am totally helpless. i guess i need to quite using cpanel and cloudlinux soon if i cant solve this load problem. here is my server config cpu E5-1620v2 - ram 16GB. whole dedicated server is my and i use two vps on that server another one is only for storage.