Every extension that does something to a website will slow down
every web browser in these useless tests. They are modifying network requests and how the website looks, and that takes away something on the test.
I tested on Firefox AdGuard and then uBO. Result I got was exactly the same.
Btw another reason why I don't trust Speedometer 3.1 results are valid. With Chrome Mask enabled, result is slightly higher than with it being disabled. Not by a lot, but results are consistent every time I tested.
Chrome Mask enabled:
View attachment 297987
Chrome Mask disabled:
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