As a general rule, no. Especially if you use the "sub-streams" that most cameras broadcast. BI will use both the primary and sub streams very efficiently. It will record the primary streams as directed to ensure the highest quality capture, but it will use the substreams to run the "trigger" algorithms and for showing small preview screens on the GUI. This saves both CPU cycles and network bandwidth. I am currently running about 12 cameras on a older i7-6400 CPU and my system sits at about 15% CPU usage. There are many users on this forum that are running 30+ cameras on even older hardware without any issues. However, if you don't use substreams this will cause more CPUs cycles to be used because it is running the "trigger" algorithms on a much higher resolution stream. That takes more computing power to do the same thing. My system would probably run at about 30% CPU usage if I didn't use the substreams option.
You can also add optional things like Deepstack which is a third party AI detection system that helps cut down on false triggers. If your cameras have AI built in you won't need this. But AI is extremely beneficial in cutting down false triggers so many people run Deepstack if their cameras don't have AI built in. Deepstack certainly adds a lot more CPU and GPU usage vs running just BI alone - especially as you add more cameras. Deepstack also does not have to be run on the same computer as BI however. But if your computer as enough CPU/GPU power to handle both, then you can have both running on the same machine to be more efficient. I personally don't run Deepstack because most of my cameras have AI built in, so I cannot give accurate estimates about how much more processing power it requires. However there are plenty of users on the forum that run both BI and Deepstack on the same computer, so it doesn't require extremely high system specs.
Does BI run a server-side and client-side setup. Am I able to only install the recording server on the server, and the client for viewing on other machines? It looked like I had to just run It as one package.
There is only one instance of BI software running on a system. There is no "server" software and "client" software. If you want to hook a monitor or TV up to the BI computer and use it as your primary camera display/GUI, you can do that. However BI offers a wide range of avenues to access the camera feeds and recordings outside of just local viewing. Most of us want to be able to view the cameras on multiple devices and BI has plenty of ways to accomplish this. I have several cheap Amazon tablets around my house that display the camera feeds full time and occasionally I want to pull up the cameras on my other computers/laptops as well. I use the free BI web interface to accomplish this. On my tablets, I normally display a full screen interface that shows the overview of all my cameras (and nothing else), and when I click on a camera feed it will then show that one camera feed full screen.
I also use the paid BI app on my personal cell phone. This is because I find it quicker and more convenient to open and use the app vs using the BI web interface. Things like viewing past recordings, triggers, etc. are all slightly easier on the app IMHO. However I could do all of this using the free web interface instead of the paid app if I wanted to. In fact I didn't buy the BI app for a long time and just viewed everything on a browser on my phone. Eventually bought the app and I'm very satisfied with my purchase.
My BI computer actually sits in a closet (along with my automation computer and firewall computer) and I don't use this machine to view my system. While I have a local monitor and keyboard that I can use to access these machines, I really only use it for maintenance. Instead I use all the other ways I just shared to access my system. I can also RDP into my BI machine when I want to change settings, add cameras, etc. That being said, I could optionally buy another BI license and run the full BI software on another computer and it would run in tandem with my main BI machine/software and I could make changes that way. Obviously I don't see any benefit in doing that when I can just RDP into the BI machine and access the BI program that way, but BI offers the flexibility to run tandem BI programs together should you have some use case that warrants that.