Can you check if the Adguard desktop app still slows down the connection? they must have improved it in the last two years since this discussion, there is a nice offer on stacksocial which brings down the price for Family Plan Lifetime version to $16 after coupon.
Things have improved a lot. Even I grabbed a lifetime Standard license a couple of weeks ago from an online shop in my country in case the MV3 version of adblocking extensions don't fulfill my needs.
The current beta version of Adguard for Windows runs faster than the stable version for me.
I still notice a slight delay but it's acceptable. I won't recommend using it with an AV that also does HTTPS scanning. It slows down browsing speed significantly in my experience. Adguard & Kaspersky both like to use CPU too. It's wise to let only one product do HTTPS scanning and in this case Adguard.
I hope Adguard can make further improvements to reduce CPU usage. This is one area where I'm not fully satisfied yet.
But yeah, if you can get a family plan lifetime license for only $16 then go for it.