That should already be disabled in Tor Browser as we ship it, no?
+ // We shouldn't leak autocomplete result in the private context.+ if (!Services.prefs.getBoolPref("browser.urlbar.speculativeConnect.enabled") ||+ this.input.inPrivateContext) {
Trac: Summary: Disable preloading of URLs in ESR59 since it's useless in Tor Browser context to Disable preloading of URLs in ESR60 since it's useless in Tor Browser context
The code changed slightly due to https://bugzilla.mozilla.org/show_bug.cgi?id=1355443, but it is disabled due to Tor Browser being in private browsing mode. (I've not thought about whether it is actually a good thing to do but I think we are good here following Mozilla).
Trac: Resolution: N/Ato worksforme Status: needs_information to closed