I've had the exact same "stuck Safari logo" issues since upgrading to High Sierra. So I attempted the VRAM restart (holding down Option/Alt + Command + P + R) while booting my computer, but that didn't work. I attempted the killall Safari command in Terminal, but that only worked temporarily – once I shut down Safari and restarted it, the logo got stuck again.
The winner for me, unfortunately, was disabling Handoff. Please note to all of you that are trying this "fix" that you have to disable Handoff on ALL devices! Not just your MacBook! If you're handing off / sharing between your MacBook and your iPhone, make sure you're going into General Settings on your iPhone and disabling as well.
This is more of a vent post toward Apple, because this isn't right that we should have to disable this feature. I use it quite frequently and really enjoy it. Unfortunately for me, the logo issue took priority as I use Gmail for work and download hundreds of documents per day. My screen was literally filled with stuck logos a matter of 20 minutes.
What I also found odd was... In Gmail, I have my shortcuts enabled so that when I press Shift + C, a new email should appear but in a SEPARATE tear-away window from my Safari browser. Whenever I tried using this shortcut, I received the error message "Oops! You must have a pop-up blocker enabled", etc. etc. Which is not the case... My pop-up blockers were disabled in my Safari settings, and any place elsewhere that I could find.
Would love it if Apple would send an update to fix this, or for someone to share any other resolution other than turning off Handoff!