Looks nice, but "lighter"... I'll have to see it to believe it. I feel like every browser has been claiming efficiency improvements for years when in reality they use more computing resources than ever before.
Their threading model looks promising. Chrome's naive way of one process per tab just wastes RAM and puts strain on the kernel. I complained about that from the start, and I was also annoyed when Safari adopted it.
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And also on Safari

Besides, uBlock Origin definitely seems lighter than AdBlock and ABP, at least in my experience.