That's not how you measure if an Antivirus is heavy or not. It's about how fast or slow it acts when scanning files as you are installing a program, launching programs, visiting websites, uncompressing files, copying large amounts of data, etc.
Do you really think AV-Comparatives opens task manager, checks the RAM and CPU usage at idle and score the performance of security solutions that way?
I could care less about RAM usage in today's world where we have lots of RAM on most computers. I am not going to start a flame war by telling you how heavy Windows Defender is. I could feel I downgraded my laptop the moment I use defender and no, it's not a slow laptop by any means, here are the specs:
Alienware m15 R7 | AMD Ryzen 9 6900HX | Micron 64 GB 4800 MHz DDR5 RAM | GeForce RTX 3080 Ti 16 GB GDDR6 | 15.6" QHD 240Hz 2ms 400-Nit ComfortView Plus G-SYNC Screen | WD_BLACK SN850X 2TB + 4TB SSDs | Intel Wi-Fi 6E AX210 | Windows 11 Pro