It does send your IP address to Google, when you download the filter. And I can't tell if "Enhanced Protection" is enabled which actually sends your URLs to Google.
I couldn't find Browser.safebrowsing.remoteLookups in my about:config. Does it still apply?
upd: I am searching for it in the Firefox sources now. Just for curiosity: there are 117512 files in 8610 directories totaling 743 MB, and search in files is really slow even on SSD.
browser.safebrowsing.remoteLookups works indeed, I could confirm this using Fiddler. For some reason, Notepad++ couldn't find a mention of 'remoteLookups' in sources.
> time egrep -Rni remotelookup .
./toolkit/devtools/gcli/source/lib/gcli/types/selection.js:81: spec.remoteLookup = (typeof this.lookup === 'function');
./toolkit/devtools/gcli/source/lib/gcli/types/selection.js:128: if (this.remoteLookup) {
egrep -Rni remotelookup . 2.01s user 0.32s system 99% cpu 2.346 total
A key that's not in the config file uses the defaults. You can just add the key by going into about:config , right clicking anywhere in the list, and choosing New, and in this case, boolean, and set it to false.