I tried this speed test and 1password made no difference - in fact in one run it was faster than without!!!!
With the same set up two successive runs gave 13±1.4 and 22±7.1 so take results with a grain of salt.
re 1password I use it so it is connected to the mac application and not the pure browser extension.
An extension that does slow things down is Dark Reader (down to 5) Orions tweaks are much faster not giving a noticeable slowdown however the benchmark site does show the m,ain reason I still use Dark Reader - with Orion tweaks the start button and the results are dark grey on black - so not readable