As the title says, for my Rainmeter stuff I need the hwinfo thing running to get the sensor data, however running it in the background, causes my whole system to have these small 1 second micro-freezes every couple of seconds.
I assume that reading some of your sensors causing this issue, but without further details (a screenshot of the sensors list at least) it's difficult to give exact advice.
A common issue is the disk sensor, so you might try to disable it: right-click on the "S.M.A.R.T." sensor heading and choose Disable Monitoring.
There's no reason for having a sensor to report total amount of graphics memory as this is a value that doesn't change.
You can see the total amount of GPU memory in HWiNFO in System Summary or in the main window.