I'm just gonna say this as a person who uses ABP and has not done any low level memory analysis: browsing using ABP saves me much more time and makes my browsing much quicker:

-ads take so long to load and when ABP is not enabled bogs down my browser hard core

-when watching videos I have to wait 3-20 seconds for them to load, with ABP enabled I do not have to wait at all

It consistently saves me several minutes every day. If it adds a few extra milliseconds to load some style sheets I have never, ever noticed.