Worth upgrading, but won't reduce your CPU usage.
Honestly, in your case it's more that BI is targeted\optimised for Intel and\or Nvidia users, all the decoding and encoding will be using the CPU. (Same boat as most H.265 users)
If you are trying to use a decent frame rate and\or high resolutions, then the CPU just won't be up for the task.
We could blame BI, but I can't think of any alternatives with your hardware as most alternatives either use NVIDIA GPU or Intel CPU's with Quicksync.
Consider investing $200-$300 in a decent spec refurb i5 from eBay. 4gb RAM is heaps. Spinning disk is also fine, if it is 7200rpm or higher.
Getting a dedicated GPU for BI is overkill, unless you CAM's are H.265, as BI can't yet decode these with Intel Quicksyc, so need to use CPU or NVIDIA GPU if that is required.
PS: Last time I used a Reolink you could disable\turn off most of the discovery crap.