You should also look at Optimizing Blue Iris's CPU Usage to get the most out of the hardware you have.
But if you are trying to sort the minimum CPU and GPU you can get away with or trying to justify the cost of an upgrade I should note it is almost impossible to get a definitive improvement number of X setup over Y unless you have both running side my side looking at the same cams. Things like the amount of motion the cams are seeing, overlays and other features in use factor in too. However this page Blue Iris Performance Statistics has a sortable and filterable table of config and load data collected from around 1400 user servers. But that still just gets you in the ballpark.
For instance I have this i7-4790 I bought used almost 5 years ago now with 10 outdoor cams that was running 50-60% CPU when I looked at it the other day when it was relatively calm. Today it looks like this, maxing out about 72%
|Iris2 load and config|
I built a i7-8700 with those same 10 cams to replace the 4790 PC. Even after adding another 6MP cam it was running 20-30% CPU during the same period as the above. Today it is maxing about 21%
|Iris6 load and config|
This one is close to max with 9 outdoor and 3 indoor cams on it.
|Iris3 load and config|
|Iris5 load and config|
And just to show the diff motion can make, this one with 23 active and 1 offline indoor cams that could handle a few more.
|Iris4 load and config.|
Update time to shuffle cams again. Having 27 indoor cams pushing almost 1000 MP/s is maxing Iris4
Wow you wonder how much diff an upgrade can make. I got a PC with a 10th Gen Intel Core i7-10700 8-Core Processor running at 2.8Ghz with just the onboard Intel 630 graphics to start with on Prime Day. Cost less than the last 8th gen i7 I bought with half the RAM. Installed latest BI 5.
It is replacing 6th gen i7 4-Core at 3.4Ghz with a Geforce 730 running BI 4 (Iris 4 above) with a bit more optimization and less cams from previous tests.
Same RAM and SSD C drive with spinning for storage.
I imported settings from the old to the new so they are identical and running side by side processing exactly the same streams from 22 active indoor cams.
Old system 13 to 34% CPU for Blue Iris
New system 3 to 4%!
Note the % reported by BI is lower than Task Manager by around 3% on both.
|Iris7 load picture|
I should be able to pull the other indoor cams back onto this server and even run DeepStack on it without maxing it out.