when you open JRealtime in the backend it consume resources only if you use the Realtime Stats. For any other feature it doesn't consume resources. If i'm right, even Easyblog has a data stream that could consume resources in frontend.
Refer to this FAQ: https://storejextensions.org/faq/does-the-component-consume-server-resources-when-active.html
where it's already explained almost everything.
If you have not 1%, you have to:
- Download again the latest package from your reserved area
- Install it again
- Clear the Joomla cache
If you set 1% as a server load, it means that JRealtime will consume almost zero resources. Thus if you still experiment high page load time probably there is another reason.