I used Novabench to test WD and found it the slowest, Avast free one of the fastest, Kaspersky Standard only slightly slower (but Kaspersky Free, which I'm told has been phased out, the fastest), and Bitdefender free in the middle.
Meanwhile, based on feel, WD feels fast initially, and then after that I can sense the slowdown when browsing folders, etc. Meanwhile, for some reason, Kaspersky Free and Standard feel faster than Avast free.
When I tried to harden WD, it led to several complications, like not being able to access some folders containing documents. I think this is one reason why the features are not yet turned on by default, as the company is probably still working on making WD better.
About browser security extensions, someone told me in another thread that they're not good enough, and that man-in-the-middle's still needed. In this case, WD protects Edge, and you have to figure out what to do for other browsers.
Meanwhile, various threads reveal that more malware attack without user interaction, are also found in "legitimate" websites and software, can sometimes not be detected, felt, or seen, can stay in the background and steal information, can go for embedded software, and where damage like stealing personal data can't obviously be reversed by data backup and recovery.
That means one wants the best security programs, and that means with lots of features. But they also slow down the system, and the costs can be very high: they give you some promo rate for the first year, and then later charge you a regular rate the next. If you have to buy for several devices, it'll be like buying a new hard drive each year, and that's even with a discount for volume sales.
Meanwhile, several have been warning about privacy, but I think all security programs violate privacy by default: they have to investigate every part of the system, and to fix unidentified malware, report to servers, etc. It's like bringing your PC to a shop for repairs. Hopefully, you can see them working on it while you wait, or you have to put in guest accounts, or bring only the part that needs testing or replacing, etc.
Given that, the best I can do is to use a fast, highly-ranked AV that allows me to stack licenses to an account and buy cheap licenses from online stores. The second option is to use what's free and still faster than WD, and finally WD with browser security extensions.
While making backups regularly.